24 CFR Part 3280

24 CFR Part 3280 (up to date as of 3/29/2023)
Manufactured Home Construction and Safety Standards

24 CFR Part 3280

This content is from the eCFR and is authoritative but unofficial.

Title 24 - Housing and Urban Development
Subtitle B - Regulations Relating to Housing and Urban Development
Chapter XX - Office of Assistant Secretary for Housing - Federal Housing Commissioner,
Department of Housing and Urban Development
Part 3280 Manufactured Home Construction and Safety Standards
Subpart A General
§ 3280.1 Scope.
§ 3280.2 Definitions.
§ 3280.3 Manufactured home procedural and enforcement regulations, and consumer manual
requirements.
§ 3280.4 Incorporation by reference.
§ 3280.5 Data plate.
§ 3280.6 Serial number.
§ 3280.7 Excluded structures.
§ 3280.8 Waivers.
§ 3280.9 Interpretative bulletins.
§ 3280.10 Use of alternative construction.
§ 3280.11 Certification label.
Subpart B Planning Considerations
§ 3280.101 Scope.
§ 3280.102 Definitions.
§ 3280.103 Light and ventilation.
§ 3280.104 Ceiling heights.
§ 3280.105 Exit facilities; exterior doors.
§ 3280.106 Exit facilities; egress windows and devices.
§ 3280.107 Interior privacy.
§ 3280.108 Interior passage.
§ 3280.109 Room requirements.
§ 3280.110 Minimum room dimensions.
§ 3280.111 Toilet compartments.
§ 3280.112 Hallways.
§ 3280.113 Glass and glazed openings.
§ 3280.114 Stairways.
Subpart C Fire Safety
§ 3280.201 Scope.
§ 3280.202 Definitions.
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§ 3280.203 Flame spread limitations and fire protection requirements.
§ 3280.204 Kitchen cabinet protection.
§ 3280.205 Carpeting.
§ 3280.206 Fireblocking.
§ 3280.207 Requirements for thermal insulating materials.
§ 3280.208 Requirements for foam plastic thermal insulating materials.
§ 3280.209 Smoke alarm requirements.
§ 3280.210 Fire testing.
§ 3280.211 Carbon monoxide alarm requirements.
§ 3280.212 Factory constructed or site-built attached garages.
§ 3280.213 Factory constructed or site-built attached carports.
Subpart D Body and Frame Construction Requirements
§ 3280.301 Scope.
§ 3280.302 Definitions.
§ 3280.303 General requirements.
§ 3280.304 Materials.
§ 3280.305 Structural design requirements.
§ 3280.306 Windstorm protection.
§ 3280.307 Resistance to elements and use.
§ 3280.308 Formaldehyde emission controls for composite wood products
Subpart E Testing
§ 3280.401 Structural load tests.
§ 3280.402 Test procedures for roof trusses.
§ 3280.403 Requirements for windows, sliding glass doors, and skylights.
§ 3280.404 Standard for egress windows and devices for use in manufactured homes.
§ 3280.405 Standard for swinging exterior passage doors for use in manufactured homes.
§ 3280.406 Air chamber test methods for certification and continuing qualification of
formaldehyde emission levels.
§ 3280.407 Quality control testing, manuals, facilities, and personnel.
Subpart F Thermal Protection
§ 3280.501 Scope.
§ 3280.502 Definitions.
§ 3280.503 Materials.
§ 3280.504 Condensation control and installation of vapor retarders.
§ 3280.505 Air infiltration.
§ 3280.506 Heat loss/heat gain.
§ 3280.507 Comfort heat gain.
§ 3280.508 Heat loss, heat gain and cooling load calculations.
§ 3280.509 Criteria in absence of specific data.
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§ 3280.510 Heat loss certificate.
§ 3280.511 Comfort cooling certificate and information.
Subpart G Plumbing Systems
§ 3280.601 Scope.
§ 3280.602 Definitions.
§ 3280.603 General requirements.
§ 3280.604 Materials.
§ 3280.605 Joints and connections.
§ 3280.606 Traps and cleanouts.
§ 3280.607 Plumbing fixtures.
§ 3280.608 Hangers and supports.
§ 3280.609 Water distribution systems.
§ 3280.610 Drainage systems.
§ 3280.611 Vents and venting.
§ 3280.612 Tests and inspection.
Subpart H Heating, Cooling and Fuel Burning Systems
§ 3280.701 Scope.
§ 3280.702 Definitions.
§ 3280.703 Minimum standards.
§ 3280.704 [Reserved]
§ 3280.705 Gas piping systems.
§ 3280.706 Oil piping systems.
§ 3280.707 Heat producing appliances.
§ 3280.708 Exhaust duct system and provisions for the future installation of a clothes dryer.
§ 3280.709 Installation of appliances.
§ 3280.710 Venting, ventilation and combustion air.
§ 3280.711 Instructions.
§ 3280.712 Marking.
§ 3280.713 Accessibility.
§ 3280.714 Appliances, cooling.
§ 3280.715 Circulating air systems.
Subpart I Electrical Systems
§ 3280.801 Scope.
§ 3280.802 Definitions.
§ 3280.803 Power supply.
§ 3280.804 Disconnecting means and branch-circuit protective equipment.
§ 3280.805 Branch circuits required.
§ 3280.806 Receptacle outlets.
§ 3280.807 Fixtures and appliances.
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§ 3280.808 Wiring methods and materials.
§ 3280.809 Grounding.
§ 3280.810 Electrical testing.
§ 3280.811 Calculations.
§ 3280.812 Wiring of expandable units and dual units.
§ 3280.813 Outdoor outlets, fixtures, air-conditioning equipment, etc.
§ 3280.814 Painting of wiring.
§ 3280.815 Polarization.
§ 3280.816 Examination of equipment for safety.
Subpart J Transportation
§ 3280.901 Scope.
§ 3280.902 Definitions.
§ 3280.903 General requirements for designing the structure to withstand transportation
shock and vibration.
§ 3280.904 Specific requirements for designing the transportation system.
Subpart K Attached Manufactured Homes and Special Construction
Considerations
§ 3280.1001 Scope.
§ 3280.1002 Definitions.
§ 3280.1003 Attached manufactured home unit separation.
§ 3280.1004 Exterior walls.
§ 3280.1005 Electrical service.
§ 3280.1006 Water service.

PART 3280 - MANUFACTURED HOME CONSTRUCTION AND SAFETY
STANDARDS
Authority: 15 U.S.C. 2697, 42 U.S.C. 3535(d), 5403, and 5424.
Source: 40 FR 58752, Dec. 18, 1975, unless otherwise noted. Redesignated at 44 FR 20679, Apr. 6, 1979.

Subpart A - General
§ 3280.1 Scope.
This standard covers all equipment and installations in the design, construction, transportation, fire safety,
plumbing, heat-producing and electrical systems of manufactured homes which are designed to be used as
dwelling units. This standard seeks to the maximum extent possible to establish performance requirements. In
certain instances, however, the use of specific requirements is necessary.
[58 FR 55002, Oct. 25, 1993]

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24 CFR 3280.2

§ 3280.2 Definitions.
Definitions in this subpart are those common to all subparts of the standard and are in addition to the definitions
provided in individual parts. The definitions are as follows:
Approved, when used in connection with any material, appliance or construction, means complying with the
requirements of the Department of Housing and Urban Development.
Attached accessory building or structure means any awning, cabana, deck, ramada, storage cabinet, carport,
windbreak, garage or porch for which the attachment of such is designed by the home manufacturer to be
structurally supported by the manufactured home.
Bay window - a window assembly whose maximum horizontal projection is not more than two feet from the
plane of an exterior wall and is elevated above the floor level of the home.
Certification label means the approved form of certification by the manufacturer that, under § 3280.8, is
permanently affixed to each transportable section of each manufactured home manufactured for sale in
the United States.
Dwelling unit means one or more habitable rooms which are designed to be occupied by one family with
facilities for living, sleeping, cooking and eating.
Equipment includes materials, appliances, devices, fixtures, fittings or accessories both in the construction of,
and in the fire safety, plumbing, heat-producing and electrical systems of manufactured homes.
Federal manufactured home construction and safety standard means a reasonable standard for the construction,
design, and performance of a manufactured home which meets the needs of the public including the need
for quality, durability, and safety.
Installations means all arrangements and methods of construction, as well as fire safety, plumbing, heatproducing and electrical systems used in manufactured homes.
Labeled means a label, symbol or other identifying mark of a nationally recognized testing laboratory, inspection
agency, or other organization concerned with product evaluation that maintains periodic inspection of
production of labeled equipment or materials, and by whose labeling is indicated compliance with
nationally recognized standards or tests to determine suitable usage in a specified manner.
Length of a manufactured home means its largest overall length in the traveling mode, including cabinets and
other projections which contain interior space. Length does not include bay windows, roof projections,
overhangs, or eaves under which there is no interior space, nor does it include drawbars, couplings or
hitches.
Listed or certified means included in a list published by a nationally recognized testing laboratory, inspection
agency, or other organization concerned with product evaluation that maintains periodic inspection of
production of listed equipment or materials, and whose listing states either that the equipment or material
meets nationally recognized standards or has been tested and found suitable for use in a specified
manner.
Manufacturer means any person engaged in manufacturing or assembling manufactured homes, including any
person engaged in importing manufactured homes for resale.
Manufactured home means a structure, transportable in one or more sections, which in the traveling mode is 8
body feet or more in width or 40 body feet or more in length or which when erected on-site is 320 or more
square feet, and which is built on a permanent chassis and designed to be used as a dwelling with or
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24 CFR 3280.2 “Manufactured home construction”

without a permanent foundation when connected to the required utilities, and includes the plumbing,
heating, air-conditioning, and electrical systems contained in the structure. This term includes all
structures that meet the above requirements except the size requirements and with respect to which the
manufacturer voluntarily files a certification pursuant to § 3282.13 of this chapter and complies with the
construction and safety standards set forth in this part 3280. The term does not include any self-propelled
recreational vehicle. Calculations used to determine the number of square feet in a structure will include
the total of square feet for each transportable section comprising the completed structure and will be
based on the structure's exterior dimensions measured at the largest horizontal projections when erected
on site. These dimensions will include all expandable rooms, cabinets, and other projections containing
interior space, but do not include bay windows. Nothing in this definition should be interpreted to mean
that a manufactured home necessarily meets the requirements of HUD's Minimum Property Standards
(HUD Handbook 4900.1) or that it is automatically eligible for financing under 12 U.S.C. 1709(b).
Manufactured home construction means all activities relating to the assembly and manufacture of a
manufactured home including, but not limited to, those relating to durability, quality and safety.
Manufactured home safety means the performance of a manufactured home in such a manner that the public is
protected against any unreasonable risk of the occurrence of accidents due to the design or construction
of such manufactured home, or any unreasonable risk of death or injury to the user or to the public if such
accidents do occur.
Registered Engineer or Architect means a person licensed to practice engineering or architecture in a state and
subject to all laws and limitations imposed by the state's Board of Engineering and Architecture
Examiners and who is engaged in the professional practice of rendering service or creative work requiring
education, training and experience in engineering sciences and the application of special knowledge of
the mathematical, physical and engineering sciences in such professional or creative work as
consultation, investigation, evaluation, planning or design and supervision of construction for the purpose
of securing compliance with specifications and design for any such work.
Secretary means the Secretary of Housing and Urban Development, or an official of the Department delegated
the authority of the Secretary with respect to title VI of Pub. L. 93-383.
State includes each of the several States, the District of Columbia, the Commonwealth of Puerto Rico, Guam,
the Virgin Islands, the Canal Zone, and American Samoa.
Width of a manufactured home means its largest overall width in the traveling mode, including cabinets and
other projections which contain interior space. Width does not include bay windows, roof projections,
overhangs, or eaves under which there is no interior space.
[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 960, Jan. 4, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at
47 FR 28092, June 29, 1982; 58 FR 55002, Oct. 25, 1993; 61 FR 5216, Feb. 9, 1996; 72 FR 27228, May 14, 2007; 86 FR 2516, Jan.
12, 2021]

§ 3280.3 Manufactured home procedural and enforcement regulations, and consumer manual
requirements.
(a) A manufacturer must comply with the requirements of this part, part 3282 of this chapter, and 42 U.S.C.
5416.
(b) Consumer manuals must be in accordance with § 3282.207 of this chapter.

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24 CFR 3280.4

[86 FR 2516, Jan. 12, 2021]

§ 3280.4 Incorporation by reference.
(a) The specifications, standards, and codes of the following organizations are incorporated by reference in
24 CFR part 3280 (this Standard) pursuant to 5 U.S.C. 552(a) and 1 CFR part 51 as though set forth in full.
The incorporation by reference of these standards has been approved by the Director of the Federal
Register. If a later edition is to be enforced, the Department will publish a notification of change in the
FEDERAL REGISTER. These incorporated standards are available for purchase from the organization that
developed the standard at the corresponding addresses noted below. Incorporated standards are
available for inspection at the Office of Manufactured Housing Program, Manufactured Housing and
Construction Standards Division, U.S. Department of Housing and Urban Development, 451 Seventh Street
SW, Room B-133, Washington, DC 20410, email [email protected]. Copies of incorporated standards that are
not available from their producer organizations may be obtained from the Office of Manufactured Housing
Programs. These standards are also available for inspection at the National Archives and Records
Administration (NARA). For information on the availability of this material at NARA, email
[email protected] or go to www.archives.gov/federal-register/cfr/ibr-locations.html.
(b) Air Conditioning & Refrigeration Institute (ARI), 4100 North Fairfax Drive, Suite 200, Arlington, VA 22203,
telephone number 703-524-8800, fax number 703-528-3816, Web site: http://www.lightindustries.com/
ARI/.
(1) ANSI/ARI Standard 210/240-89, Unitary Air-Conditioning and Air-Source Heat Pump Equipment, IBR
approved for §§ 3280.511(b), 3280.703, and 3280.714(a),
(2) [Reserved]
(c) Aluminum Association (AA), 1525 Wilson Blvd., Suite 600, Arlington, VA 22209; telephone number
703-358-2960, fax number 703-358-3921; Web site: http://www.aluminum.org.
(1) Aluminum Design Manual, Specifications and Guidelines for Aluminum Structures, Part 1-A, Sixth
Edition, October 1994, IBR approved for § 3280.304(b).
(2) Aluminum Design Manual, Specifications and Guidelines for Aluminum Structures, Part 1-B, First
Edition, October 1994, IBR approved for § 3280.304(b).
(d) American Architectural Manufacturers Association (AAMA), 1827 Walden Office Square, Suite 550,
Schaumburg, IL 60173, telephone number 847-303-5664, fax number 847-303-5774, Web site:
http://www.aamanet.org.
(1) AAMA 1503.1-88, Voluntary Test Method for Thermal Transmittance and Condensation Resistance
of Windows, Doors, and Glazed Wall Sections, IBR approved for § 3280.508(e).
(2) AAMA 1600/I.S.7-00, Voluntary Specification for Skylights, 2003 IBR approved for § 3280.305(c).
(3) AAMA 1701.2-95, Voluntary Standard Primary Window and Sliding Glass Door for Utilization in
Manufactured Housing, IBR approved for §§ 3280.403(e) and 3280.404(b).
(4) AAMA 1702.2-95, Voluntary Standard Swinging Exterior Passage Door for Utilization in Manufactured
Housing, IBR approved for § 3280.405(b) and (e).
(5) AAMA Standard 1704-1985, Voluntary Standard Egress Window Systems for Utilization in
Manufactured Housing, IBR approved for § 3280.404(b).
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(6) AAMA/WDMA/CSA/101/I.S.2/A440-08 North American Fenestration Standard/Specification for
Windows, Doors and Skylights, January 2008, IBR approved for § 3280.403(b) and (e).
(7) ANSI/AAMA/NWWDA 101/I.S.2-97,Voluntary Specifications for Aluminum, Vinyl (PVC) and Wood
Windows and Glass Doors, IBR approved for § 3280.304(b).
(e) American Forest and Paper Association (AFPA), 1111 Nineteenth Street, Suite 800, Washington, DC 20036
(previously named National Forest Products Association (NFPA), telephone number 1-800-878-8878, Web
site: http://www.afandpa.org.
(1) AFPA, Design Values for Joists and Rafters 1992, IBR approved for § 3280.304(b).
(2) AFPA PS-20-70, Span Tables for Joists and Rafters, 1993, IBR approved for § 3280.304(b).
(3) ANSI/AFPA NDS-2001, National Design Specifications for Wood Construction, 2001 Edition, with
Supplement, Design Values for Wood Construction, November 30, 2001, IBR approved for §
3280.304(b).
(4) AFPA, Wood Structural Design Data, 1986 Edition with 1992 Revisions, IBR approved for §
3280.304(b).
(f) American Gas Association (AGA), 400 North Capitol Street NW., Washington, DC 20001, telephone number
202-824-7000, Web site: http://www.aga.org/Pages/default.aspx.
(1) AGA No. 3-87, Requirements for Gas Connectors for Connection of Fixed Appliances for Outdoor
Installation, Park Trailers, and Manufactured (Mobile) Homes to the Gas Supply, IBR approved for §
3280.703.
(2) [Reserved]
(g) American Hardboard Association (AHA), 1210 West NW Highway, Palatine, IL 60067, Web site:
http://hardboard.org.
(1) ANSI/AHA A135.4-1995, Basic Hardboard, IBR approved for § 3280.304(b).
(2) ANSI/AHA A135.5-1995, Prefinished Hardboard Paneling, IBR approved for § 3280.304(b).
(3) ANSI/AHA A135.6-1998, Hardboard Siding, IBR approved for § 3280.304(b).
(h) American Institute of Steel Construction (AISC), One East Wacker Drive, Chicago, IL 60601, telephone
number 312-670-2400, fax number 312-670-5403, Web site: http://www.aisc.org/.
(1) AISC-S335, 1989. Specification for Structural Steel Buildings - Allowable Stress Design and Plastic
Design (except for the following parts of this standard which are not incorporated by reference:
1.3.3, 1.3.4, 1.3.5, 1.3.6, 1.4.6, 1.5.1.5, 1.5.5, 1.6, 1.7, 1.8, 1.9, 1.10.4 through 1.10.7, 1.10.9, 1.11, 1.13,
1.14.5, 1.17.7 through 1.17.9, 1.19.1, 1.19.3, 1.20, 1.21, 1.23.7, 1.24, 1.25.1 through 1.25.5, 1.26.4,
2.3, 2.4, 2.8 through 2.10), June 1, 1989, IBR approved for §§ 3280.304(b) and 3280.305(j).
(2) [Reserved]
(i)

American Iron and Steel Institute (AISI), 25 Massachusetts Ave., NW., Suite 800, Washington, DC 20001,
telephone number 202-452-7100, Web site: http://www.steel.org.
(1) AISI, Specification for the Design of Cold-Formed Steel Structural Members, 1996, IBR approved for
§§ 3280.304(b) and 3280.305(j).
(2) [Reserved]

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(j)

24 CFR 3280.4(j)

American National Standards Institute (ANSI), 25 West 43rd Street, 4th floor, New York, NY 10018,
telephone number 212-642-4900, fax number 212-398-0023, Web site: http://www.ansi.org.
(1) ANSI A112.14.1-1975, Backflow Valves, IBR approved for § 3280.604(b).
(2) ANSI A112.19.5-1979, Trim for Water Closet, Bowls, Tanks, and Urinals, IBR approved for §
3280.604(b).
(3) ANSI/AITC A190.1-1992, For wood products - Structural Glued Laminated Timber, IBR approved for §
3280.304(b).
(4) ANSI A208.1-1999, Particleboard, IBR approved for § 3280.304(b).
(5) ANSI A208.2-2002, Medium Density Fiberboard (MDF) For Interior Applications, approved May 13,
2002, IBR approved for § 3280.304(b).
(6) ANSI B16.18-1984, Cast Copper Alloy Solder-Joint Pressure Fittings, IBR approved for § 3280.604(b).
(7) ANSI C72.1-1972, section 4.3.1, Household Automatic Electric Storage Type Water Heaters, IBR
approved for § 3280.707(d).
(8) ANSI/IAS LC 1-1997, Fuel Gas Piping Systems Using Corrugated Stainless Steel Tubing (CSST),
approved October 28, 1996, IBR approved for § 3280.705(b).
(9) ANSI Z21.1-2000, Household Cooking Gas Appliances, IBR approved for § 3280.703.
(10) ANSI Z21.5.1-1999, Gas Clothes Dryers Volume 1, Type 1 Clothes Dryers, with Addendum
Z21.5.1a-1999, IBR approved for § 3280.703.
(11) ANSI Z21.10.1-1998, Gas Water Heaters - Volume 1, Storage Water Heaters with Input Ratings of
75,000 BTU per hour or Less, with Addendum Z21.10.1a-2000, IBR approved for §§ 3280.703 and
3280.707(d).
(12) ANSI Z21.15-1997, Manually Operated Gas Valves for Appliances, Appliance Connector Valves and
Hose End Valves, IBR approved for §§ 3280.703 and 3280.705(c).
(13) ANSI Z21.19-1990, with Addendum ANSI Z21.19a-1992 and Z21.19b-1995, Refrigerators Using Gas
Fuel, IBR approved for § 3280.703.
(14) ANSI Z21.20 with Addendum Z21.20a-2000, Automatic Gas Ignition Systems and Components, IBR
approved for § 3280.703.
(15) ANSI Z21.21-2000, Automatic Valves for Gas Appliances, IBR approved for § 3280.703.
(16) ANSI Z21.22-1999, Relief Valves for Hot Water Supply Systems, IBR approved for §§ 3280.604(b) and
3280.703.
(17) ANSI Z21.23-1993, Gas Appliance Thermostats, approved August 10, 1993, IBR approved for §
3280.703.
(18) ANSI Z21.24-1997/CGA 6.10-M97, Connectors for Gas Appliances, IBR approved for § 3280.703.
(19) ANSI Z21.40.1-1996/CGA 2.91-M96, Gas-Fired, Heat Activated Air Conditioning and Heat Pump
Appliances, IBR approved for §§ 3280.703 and 3280.714(a).
(20) ANSI Z21.47-1990 with Addendum Z21.47a-1990 and Z21.47b-1992, Gas-Fired Central Furnaces
(Except Direct Vent System Central Furnaces), IBR approved for § 3280.703.

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(21) ANSI Z34.1-1993, Third-Party Certification Programs for Products, Processes, and Services, IBR
approved for §§ 3280.403(e) and 3280.405(e).
(22) ANSI Z97.1-2004, Standard for Safety Glazing Materials used in Buildings - Safety Performance
Specifications and Methods of Test, copyright 2004, IBR approved for §§ 3280.113(c), 3280.304(b),
3280.403(d)(1), 3280.604(b), and 3280.607(b).
(23) ANSI Z124.1-1987, Plastic Bathtub Units with Addendum Z124.1a-1990 and Z124.1b-1991, IBR
approved for § 3280.604(b).
(24) ANSI Z124.2-1987, Plastic Shower Receptors and Shower Stalls with Addendum Z124.2a-1990, IBR
approved for § 3280.604(b).
(25) ANSI Z124.3-1986, Plastic Lavatories with Addendum Z124.3a-1990, IBR approved for §
3280.604(b).
(26) ANSI Z124.4-1986, Plastic Water Closets, Bowls, and Tanks with Addenda Z124.4a-1990, IBR
approved for § 3280.604(b).
(27) ANSI Z124.5-1997, Plastic Toilet (Water Closets) Seats, IBR approved for § 3280.604(b).
(28) ANSI Z124.7-1997, Prefabricated Plastic Spa Shells, IBR approved for § 3280.604(b).
(29) ANSI Z-124.9-1994, Plastic Urinal Fixtures, IBR approved for § 3280.604(b).
(k) The Engineered Wood Association (APA) (formerly the American Plywood Association), 7011 South 19th
Street, Tacoma, WA 98411, telephone number 253-565-6600, fax number 253-565-7265, Web site:
http://www.apawood.org.
(1) APA D410A-2004, Panel Design Specification, IBR approved for § 3280.304(b).
(2) APA E30P-1996, APA Design/Construction Guide, Residential and Commercial Structures, IBR
approved for § 3280.304(b).
(3) APA E30R, Engineered Wood Construction Guide, revised January 2001, IBR approved for §
3280.304(b).
(4) APA H815E-1995 (PDS Supplement #5), Design and Fabrication of All-Plywood Beams, IBR approved
for § 3280.304(b).
(5) APA S 811M-1990 (PDS Supplement 1), Design and Fabrication of Plywood Curved Panels, IBR
approved for § 3280.304(b).
(6) APA S 812R, Design and Fabrication of Glued Plywood-Lumber Beams, revised November 1998,
Supplement #2, July 1992 IBR approved for § 3280.304.
(7) APA U 813L, Design and Fabrication of Plywood Stressed-Skin Panels, revised April 1996,
Supplement # 3, August 1992, IBR approved for § 3280.304(b).
(8) APA U 814H, Design and Fabrication of Plywood, Sandwiched Panels, revised September 1993,
Supplement #4, March 1990, IBR approved for § 3280.304(b).
(l)

American Society of Civil Engineers (ASCE), 1801 Alexander Bell Drive, Reston, VA 20191, telephone
number 800-548-2723, Web site: http://www.asce.org.
(1) ANSI/ASCE 7-88, Minimum Design Loads for Buildings and Other Structures, IBR approved for §§
3280.5(f), 3280.304(b), and 3280.305(c).

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(2) SEI/ASCE 8-02, Specification for the Design of Cold-Formed Stainless Steel Structural Members,
2002, IBR approved for §§ 3280.304(b) and 3280.305(j).
(3) ASCE 19-96, Structural Applications of Steel Cables for Buildings, IBR approved for § 3280.304(b).
(m) American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), 1791 Tullie Circle
NE., Atlanta, GA 30329, telephone number 404-636-8400, fax number 404-321-5478, Web site:
https://www.ashrae.org/home/.
(1) 1997 ASHRAE Handbook of Fundamentals, Inch-Pound Edition (1997), chapters 22 through 27,
(except for the following parts of this standard that are not incorporated by reference: 23.1 Steel
Frame Construction; 23.2 Masonry Construction; 23.3 Foundations and Floor Systems; 23.15 Pipes;
23.17 Tanks, Vessels, and Equipment; 23.18 Refrigerated Rooms and Buildings; 24.18 Mechanical
and Industrial Systems; 25.19 Commercial Building Envelope Leakage; 27.9 Calculation of Heat Loss
from Crawl Spaces). IBR approved for §§ 3280.508(a), 3280.508(e), and 3280.511(a).
(2) ANSI/ASHRAE 62.2-2010, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential
Buildings, copyright 2010 IBR approved for § 3280.103(d).
(n) ASME (formally the American Society of Mechanical Engineers), Two Park Avenue, New York, NY
10016-5990, telephone number 800-843-2763, Web site: http://www.asme.org/.
(1) ASME A112.1.2-1991, Air Gaps in Plumbing Systems, IBR approved for § 3280.604(b).
(2) ANSI/ASME A112.4.1-1993, Water Heater Relief Valve Drain Tubes, IBR approved for § 3280.604(b).
(3) ANSI/ASME A112.4.3-1999, Plastic Fittings for Connecting Water Closets to the Sanitary Drainage
System, IBR approved for § 3280.604(b).
(4) ASME/ANSI A112.18.1M-1989, Plumbing Fixture Fittings, IBR approved for § 3280.604(b).
(5) ASME A112.18.3M-1996, Performance Requirements for Backflow Protection Devices and Systems
in Plumbing Fixture Fittings, IBR approved for § 3280.604(b).
(6) ASME A112.18.6-1999, Flexible Water Connectors, IBR approved for § 3280.604(b).
(7) ASME A112.18.7-1999, Deck Mounted Bath/Shower Transfer Valves with Integral Backflow
Protection, IBR approved for § 3280.604(b).
(8) ANSI/ASME A112.19.1M-1987, Enameled Cast Iron Plumbing Fixtures, IBR approved for §
3280.604(b).
(9) ANSI/ASME A112.19.2(M)-1990, Vitreous China Plumbing Fixtures, IBR approved for § 3280.604(b).
(10) ANSI/ASME A112.19.3M-1987, Stainless Steel Plumbing Fixtures (Designed for Residential Use), IBR
approved for § 3280.604(b).
(11) ANSI/ASME A112.19.4(M)-1984, Porcelain Enameled Formed Steel Plumbing Fixtures, IBR approved
for § 3280.604(b).
(12) ASME A112.19.6-1995, Hydraulic Performance Requirements for Water Closets and Urinals, IBR
approved for § 3280.604(b).
(13) ASME/ANSI A112.19.7M-1987, Whirlpool Bathtub Appliances, IBR approved for § 3280.604(b).
(14) ASME/ANSI A112.19.8M-1989, Suction Fittings for Use in Swimming Pools, Wading Pools, Spas, Hot
Tubs, and Whirlpool Bathtub Appliances, IBR approved for § 3280.604(b).
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24 CFR 3280.4(n)(15)

(15) ASME A112.19.9M-1991, Non-Vitreous Ceramic Plumbing Fixtures, IBR approved for § 3280.604(b).
(16) ASME A112.19.10-1994, Dual Flush Devices for Water Closets, IBR approved for § 3280.604(b).
(17) ANSI/ASME A112.21.3M-1985, Hydrants for Utility and Maintenance Use, IBR approved for §
3280.604(b).
(18) ANSI/ASME B1.20.1-1983, Pipe Threads, General Purpose (Inch), IBR approved for §§ 3280.604(b),
3280.703, 3280.705(e), and 3280.706(d).
(19) ANSI/ASME B16.3-1992, Malleable Iron Threaded Fittings, IBR approved for § 3280.604(b).
(20) ANSI/ASME B16.4-1992, Gray Iron Threaded Fittings, IBR approved for § 3280.604(b).
(21) ANSI/ASME B16.15-1985, Cast Bronze Threaded Fittings, Classes 125 and 250, IBR approved for §
3280.604(b).
(22) ASME/ANSI B16.22-1989, Wrought-Copper and Copper Alloy Solder-Joint Pressure Fitting, IBR
approved for § 3280.604(b).
(23) ASME B16.23-1992, Cast Copper Alloy Solder-Joint Drainage Fittings-DWV, IBR approved for §
3280.604(b).
(24) ASME/ANSI B16.26-1988, Cast Copper Alloy Fittings for Flared Copper Tubes, IBR approved for §
3280.604(b).
(25) ASME/ANSI B16.29-1986, Wrought Copper and Wrought Copper Alloy Solder-Joint Drainage FittingsDWV, IBR approved for § 3280.604(b).
(26) ANSI/ASME B36.10-1979, Welding and Seamless Wrought Steel Pipe, IBR approved for §§
3280.604(b), 3280.703, 3280.705(b), and 3280.706(b).
(o) American Society of Sanitary Engineering (ASSE), 901 Canterbury, Suite A, Westlake, OH 44145, phone
number 440-835-3040, fax number 440-835-3488, Web site: http://www.asse-plumbing.org.
(1) ASSE 1001 (ANSI Approved 1990), Performance Requirements for Pipe Applied Atmospheric Type
Vacuum Breakers, IBR approved for § 3280.604(b).
(2) ASSE 1002 Revision 5-1986 (ANSI/ASSE-1979), Performance Requirements for Water Closet Flush
Tank Fill Valves (Ballcocks), IBR approved for § 3280.604(b).
(3) ASSE 1006 (ASSE/ANSI-1986), Plumbing Requirements for Residential Use (Household)
Dishwashers, IBR approved for § 3280.604(b).
(4) ASSE 1007-1986, Performance Requirements for Home Laundry Equipment, IBR approved for §
3280.604(b).
(5) ASSE 1008-1986, Performance Requirements for Household Food Waste Disposer Units, IBR
approved for § 3280.604(b).
(6) ASSE 1011-1981 (ANSI-1982), Performance Requirements for Hose Connection Vacuum Breakers,
IBR approved for § 3280.604(b).
(7) ASSE 1014-1989 (ANSI-1990), Performance Requirements for Hand-held Showers, IBR approved for
§ 3280.604(b).

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24 CFR 3280.4(o)(8)

(8) ASSE 1016-2005, Performance Requirements for Automatic Compensating Values for Individual
Shower and Tub/Shower Combinations, approved January 2005, IBR approved for §§ 3280.604(b)
and 3280.607(b).
(9) ASSE 1017-1986, Performance Requirements for Temperature Activated Mixing Valves for Primary
Domestic Use, IBR approved for § 3280.604(b).
(10) ANSI/ASSE 1019-1978, Performance Requirements for Wall Hydrants, Frost Proof Automatic
Draining, Anti-Backflow Types, IBR approved for § 3280.604(b).
(11) ASSE 1023 (ANSI/ASSE-1979), Performance Requirements for Hot Water Dispensers, Household
Storage Type Electrical, IBR approved for § 3280.604(b).
(12) ASSE 1025 (ANSI/ASSE-1978), Performance Requirements for Diverters for Plumbing Faucets with
Hose Spray, Anti-Siphon Type, Residential Applications, IBR approved for § 3280.604(b).
(13) ASSE 1037-1990 (ANSI-1990), Performance Requirements for Pressurized Flushing Devices
(Flushometers) for Plumbing Fixtures, IBR approved for § 3280.604(b).
(14) ASSE 1051 Revised 1996 (ANSI 1998), Performance Requirements for Air Admittance Valves for
Plumbing Drainage Systems - Fixture and Branch Devices, IBR approved for § 3280.604(b).
(15) ASSE 1070-2004, Performance Requirements for Water Temperature Limiting Devices, IBR approved
for §§ 3280.604(b) and 3280.607(b).
(p) ASTM, International,100 Barr Harbor Drive, West Conshohocken, PA 19428, (610) 832-9500, fax number
610-832-9555, Web site: http://www.astm.org.
(1) ASTM A53-93. Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and
Seamless, IBR approved for §§ 3280.604(b) and 3280.703.
(2) ASTM A74-92, Standard Specification for Cast Iron Soil Pipe and Fittings, IBR approved for §
3280.604(b).
(3) ASTM A539-99, Standard Specification for Electric-Resistance-Welded Coiled Steel Tubing for Gas
and Fuel Oil Lines, IBR approved for §§ 3280.703, 3280.705(b), and § 3280.706(b).
(4) ASTM B42-93, Standard Specification for Seamless Copper Pipe, Standard Sizes, IBR approved for
§§ 3280.604 and 3280.703.
(5) ASTM B43-91, Standard Specification for Seamless Red Brass Pipe, Standard Sizes, IBR approved for
§§ 3280.604(b) and 3280.705(b).
(6) ASTM B88-93, Standard Specification for Seamless Copper Water Tube, IBR approved for §§
3280.604, 3280.703, 3280.705(b), and 3280.706(b).
(7) ASTM B251-93, Standard Specification for General Requirements for Wrought Seamless Copper and
Copper-Alloy Tube, IBR approved for §§ 3280.604 and 3280.703.
(8) ASTM B280-95a, Standard Specification for Seamless Copper Tube for Air Conditioning and
Refrigeration Field Service, IBR approved for §§ 3280.703, 3280.705(b), and 3280.706(b).
(9) ASTM B306-92, Standard Specification for Copper Drainage Tube (DWV), IBR approved for §
3280.604(b).

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24 CFR 3280.4(p)(10)

(10) ASTM C 36/C 36M-99, Standard Specification for Gypsum Wallboard, 1999, IBR approved for §
3280.304.
(11) ASTM C564-97, Standard Specification for Rubber Gaskets for Case Iron Soil Pipe and Fittings,
approved December 10, 1997, IBR approved for §§ 3280.604(b) and 3280.611(d).
(12) ASTM C920-02, Standard Specification for Elastomeric Joint Sealants, approved January 10, 2002,
IBR approved for § 3280.611(d).
(13) ASTM D781-68 (Reapproved 1973), Standard Test Methods for Puncture and Stiffness of
Paperboard, and Corrugated and Solid Fiberboard, IBR approved for §§ 3280.304(b), and
3280.305(g).
(14) ASTM D2235-88, Standard Specification for Solvent Cement for Acrylonitrile-Butadiene-Styrene (ABS)
Plastic Pipe and Fittings, IBR approved for § 3280.604(b).
(15) ASTM D2564-91a, Standard Specification for Solvent Cements for Poly (Vinyl Chloride) (PVC) Plastic
Piping Systems, IBR approved for § 3280.604(b).
(16) ASTM D2661-91, Standard Specification for Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40
Plastic Drain, Waste, and Vent Pipe and Fittings, IBR approved for § 3280.604(b).
(17) ASTM D2665-91b, Standard Specification for Poly (Vinyl Chloride) (PVC) Plastic Drain, Waste, and
Vent Pipe and Fittings, IBR approved for § 3280.604(b).
(18) ASTM D2846-92, Standard Specification for Chlorinated Poly (Vinyl Chloride) (CPVC) Plastic Hot- and
Cold-Water Distribution Systems, IBR approved for § 3280.604(b).
(19) ASTM D3309-92a, Standard Specification for Polybutylene (PB) Plastic Hot- and Cold-Water
Distribution Systems, IBR approved for § 3280.604(b).
(20) ASTM D3311-92, Standard Specification for Drain, Waste, and Vent (DWV) Plastic Fittings Patterns,
IBR approved for § 3280.604(b).
(21) ASTM D3953-97, Standard Specification for Strapping, Flat Steel, and Seals, approved April 10, 1997,
IBR approved for §§ 3280.306(b) and 3280.306(g).
(22) ASTM D4442-92 (Reapproved 1997), Standard Test Methods for Direct Moisture Content
Measurement of Wood and Wood-Base Materials, IBR approved for § 3280.304(b).
(23) ASTM D4444-92, Standard Test Methods for Use and Calibration of Hand-Held Moisture Meters, IBR
approved for § 3280.304(b).
(24) ASTM D4635-01, Standard Specification for Polyethylene Films Made from Low-Density Polyethylene
for General Use and Packaging Applications, approved June 10, 2001, IBR approved for §
3280.611(d).
(25) ASTM D6007-14, Standard Test Method for Determining Formaldehyde Concentrations in Air from
Wood Products Using a Small Air Chamber, approved October 1, 2014; IBR approved for §
3280.406(b).
(26) ASTM E84-01, Standard Test Method for Surface Burning Characteristics of Building Materials, 2001,
IBR approved for § 3280.203(a).
(27) ASTM E 119-05, Standard Test Methods for Fire Tests of Building Construction and Materials,
approved September 15, 2005, IBR approved for § 3280.1003(a).
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24 CFR 3280.4(p)(28)

(28) ASTM E 96-95 Standard Test Methods for Water Vapor Transmission of Materials, IBR approved for §
3280.504(a).
(29) ASTM E 162-94, Standard Test Method for Surface Flammability of Materials Using a Radiant Heat
Energy Source, IBR approved for § 3280.203(a).
(30) ASTM E 773-97, Standard Test Methods for Accelerated Weathering of Sealed Insulating Glass Units,
IBR approved for § 3280.403(d).
(31) ASTM E 774-97, Standard Specification for the Classification of the Durability of Sealed Insulating
Glass Units, IBR approved for § 3280.403(d).
(32) ASTM E1333-14, Standard Test Method for Determining Formaldehyde Concentrations in Air and
Emission Rates from Wood Products Using a Large Air Chamber, approved October 1, 2014; IBR
approved for § 3280.406(b).
(33) ASTM F628-91, Standard Specification for Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40, Plastic
Drain, Waste, and Vent Pipe with a Cellular Core, IBR approved for § 3280.604(b).
(34) ASTM F876-10, Standard Specification for Crosslinked Polyethylene (PEX) Tubing, approved February
10, 2010, IBR approved for § 3280.604(b).
(35) ASTM F877-07, Standard Specification for Crosslinked Polyethylene (PEX) Plastic Hot- and ColdWater Distribution Systems, approved February 1, 2007, IBR approved for § 3280.604(b).
(q) Cast Iron Soil Pipe Institute (CISPI), 1064 Delaware Avenue SE, Atlanta, GA 30316, telephone number
404-622-0073, fax number 404-973-2845, Web site: http://www.cispi.org/.
(1) CISPI-301-90, Standard Specification for Hubless Cast Iron Soil Pipe and Fittings for Sanitary and
Storm Drain, Waste, and Vent Piping Applications, IBR approved for § 3280.604(b).
(2) CISPI-HSN-85, Specification for Neoprene Rubber Gaskets for HUB and Spigot Cast Iron Soil Pipe and
Fittings, IBR approved for §§ 3280.604, 3280.611(d).
(r) FS - Federal Specifications, General Services Administration, Specifications Branch, Room 6039, GSA
Building, 7th and D Streets, SW., Washington, DC 20407.
(1) FS WW-P-541E/GEN-1980, Plumbing Fixtures (General Specifications), IBR approved for §
3280.604(b).
(2) FS ZZ-R-765B-1970, Silicone Rubber, (with 1971 Amendment), IBR approved for § 3280.611(d).
(s) HPVA (previously HPMA) - Hardwood Plywood and Veneer Association (HPVA) (previously named
Hardwood Plywood Manufacturers Association (HPMA), 1825 Michael Faraday Drive, Reston, VA 22090,
telephone number 703-435-2900, fax number 703-435-2537, Web site: http://www.hpva.org/.
(1) ANSI/HPVA HP-1-1994 (Approved 1995), American National Standard for Hardwood and Decorative
Plywood, IBR approved for § 3280.304(b).
(2) HP-SG-96, Structural Design Guide for Hardwood Plywood Wall Panels, revised 1996, IBR approved
for § 3280.304(b).
(t) HUD User, 11491 Sunset Hills Road, Reston, VA 20190-5254.
(1) HUD User No. 0005945, Overall U-values and Heating/Cooling Loads - Manufactured Homes,
February 1992. IBR approved for § 3280.508(b).
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24 CFR 3280.4(t)(2)

(2) [Reserved]
(u) IIT Research Institute (IITRI), 10 West 35th Street, Chicago, IL 60616, telephone number 312-567-4000,
Web site: http://www.iitri.org/.
(1) IITRI Fire and Safety Research Project J-6461 “Development of Mobile Home Fire Test Methods to
Judge the Fire-Safe Performance of Foam Plastic Sheathing and Cavity Insulation”, 1979, IBR
approved for § 3280.207(a).
(2) [Reserved]
(v) International Association of Plumbing and Mechanical Officials (IAPMO), 4755 East Philadelphia Street,
Ontario, CA 91716, telephone number 909-472-4100, fax number 909-472-4150, Web site:
http://www.iapmo.org.
(1) IAPMO PS 2-89, Material and Property Standard for Cast Brass and Tubing P-Traps, IBR approved for
§ 3280.604(b).
(2) IAPMO PS 4-90, Material and Property Standard for Drains for Prefabricated and Precast Showers,
IBR approved for § 3280.604(b).
(3) IAPMO PS 5-84, Material and Property Standard for Special Cast Iron Fittings, IBR approved for §
3280.604(b).
(4) IAPMO PS 9-84, Material and Property Standard for Diversion Tees and Twin Waste Elbow, IBR
approved for § 3280.604(b).
(5) IAPMO PS 14-89, Material and Property Standard for Flexible Metallic Water Connectors, IBR
approved for § 3280.604(b).
(6) IAPMO PS 23-89, Material and Property Standard for Dishwasher Drain Airgaps, IBR approved for §
3280.604(b).
(7) IAPMO PS 31-91, Material and Property Standards for Backflow Prevention Assemblies, IBR
approved for § 3280.604(b).
(8) IAPMO TSC 9-97, Standard for Gas Supply Connectors for Manufactured Homes, IBR approved for §
3280.703.
(9) IAPMO TSC 22-85, Standard for Porcelain Enameled Formed Steel Plumbing Fixtures, IBR approved
for § 3280.604(b).
(w) Military Specifications and Standards, Naval Publications and Forms Center (MIL), 5801 Tabor Avenue,
Philadelphia, PA 19120.
(1) MIL-L-10547E-1975, Liners, Case, and Sheet, Overwrap; Water-Vapor Proof or Waterproof, Flexible,
IBR approved for § 3280.611(d).
(2) [Reserved]
(x) National Electrical Manufacturers Association (NEMA), 1300 North 17th Street, Suite 1752, Arlington, VA
22209, telephone number 703-841-3200, fax number 703-841-5900, Web site: http://www.nema.org/
Pages/default.aspx.
(1) ANSI/NEMA WD-6-1997 Wiring Devices-Dimensional Specifications, IBR approved for § 3280.803(f).
(2) [Reserved]
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24 CFR 3280.4(y)

(y) International Code Council Evaluation Service (NER), (previously known as National Evaluation Service),
5360 Workman Mill Road, Whittier, CA 90601-0543, telephone number 1-800-423-6587, ext. 66546, fax
number 562-695-4694, Web site: http://www.icc-es.org.
(1) NER-272, National Evaluation Report, Power Driven Staples, Nails, and Allied Fasteners for Use in All
Types of Building Construction, Reissued September 1, 1997, IBR approved for § 3280.304(b).
(2) [Reserved]
(z) National Fenestration Rating Council (NFRC), 6305 Ivy Lane, Suite 140, Greenbelt, MD 20770, telephone
number 301-589-1776, fax number 301-589-3884, Web site: http://www.nfrc.org.
(1) NFRC 100, Procedure for Determining Fenestration Product U-factors, 1997 Edition, IBR approved for
§ 3280.508(e).
(2) [Reserved]
(aa) National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA 02269, phone number
617-770-3000, fax number 617-770-0700, Web site: http://www.nfpa.org.
(1) NFPA 31, Standard for the Installation of Oil Burning Equipment, 2001, IBR approved for §§ 3280.703
and 3280.707(f).
(2) NFPA 54-2002, National Fuel Gas Code, IBR approved for § 3280.703.
(3) NFPA 58, Liquefied Petroleum Gas Code, 2001 Edition, IBR approved for §§ 3280.703 and
3280.704(b).
(4) NFPA No. 70-2005, National Electrical Code, IBR approved as follows:
(i)

Article 110.22, IBR approved for §§ 3280.803(k) and 3280.804(k).

(ii) Article 210.12(A) and (B), IBR approved for § 3280.801(b).
(iii) Article 220.61, IBR approved for § 3280.811(b).
(iv) Article 230, IBR approved for §§ 3280.803(k) and 3280.804(k).
(v) Article 250.24, IBR approved for §§ 3280.803(k) and 3280.804(k).
(vi) Article 250.26, IBR approved for §§ 3280.803(k) and 3280.804(k).
(vii) Article 250.28, IBR approved for §§ 3280.803(k) and 3280.804(k).
(viii) Article 312.2(A), IBR approved for §§ 3280.803(k) and 3280.804(k).
(ix) Table 314.16(A), IBR approved for §§ 3280.808(m) and 3280.808(q).
(x) Article 314.23(B), IBR approved for §§ 3280.808(m) and 3280.808(q).
(xi) Article 406.3, IBR approved for § 3280.807(d).
(xii) Article 410.4(D), IBR approved for § 3280.805(a).
(xiii) Article 440, IBR approved for § 3280.805(a).
(xiv) Article 440.65, IBR approved for § 3280.801(b).
(xv) Part II of Article 550, IBR approved for §§ 3280.801(a) and 3280.801(b).
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24 CFR 3280.4(aa)(4)(xvi)

(xvi) Article 550.17, IBR approved for § 3280.810(b).
(xvii) Article 550.25(a), IBR approved for § 3280.801(b).
(xviii) Article 680.70, IBR approved for §§ 3280.607(c) and 3280.801(a).
(xix) Article 680.71, IBR approved for §§ 3280.607(c) and 3280.801(a).
(xx) Articles 680.72, IBR approved for §§ 3280.607(c) and 3280.801(a).
(5) NFPA 90B, Warm Air Heating and Air Conditioning Systems, 1996 Edition, IBR approved for §
3280.703.
(6) NFPA 220, Standard on Types of Building Construction, Chapter 2: definitions of “limited
combustible” and “noncombustible material”, 1995 Edition, IBR approved for § 3280.202.
(7) NFPA 253, Standard Method of Test for Critical Radiant Flux of Floor Covering Systems Using a
Radiant Heat Energy Source, 2000, IBR approved for § 3280.207(c).
(8) NFPA 255, Standard Method of Test of Surface Burning Characteristics of Building Materials, 1996,
IBR approved for §§ 3280.203(a) and 3280.207(a).
(9) NFPA 720, Standard for Installation of Carbon Monoxide (CO) Detection and Warning Equipment,
2015 Edition, Copyright 2014, IBR approved for § 3280.211(b).
(bb) U.S. Department of Commerce, National Institute of Standards and Technology (NIST), Office of
Engineering Standards, Room A-166, Technical Building, Washington, DC 20234 and Voluntary Product
Division, 100 Bureau Drive, Stop 2100, Gaithersburg, MD 20899-2100, telephone number 301- 975-4000,
fax number 301-975-4715, Web site: http://www.nist.gov.
(1) PS 1-95, Construction and Industrial Plywood (With Typical APA Trademarks), IBR approved for §
3280.304(b).
(2) Voluntary Product Standard PS 2-04, Performance Standard for Wood-Based Structural-Use Panels,
December 2004, IBR approval for § 3280.304(b).
(cc) National Sanitation Foundation (NSF), 789 North Dixboro Road, Ann Arbor, MI 48105, telephone number
734-769-8010, fax number 734-769-0109, Web site: http://www.nsf.org.
(1) ANSI/NSF 14-1990, Plastic Piping Components and Related Materials, IBR approved for §
3280.604(b).
(2) ANSI/NSF 24-1988, Plumbing System Components for Manufactured Homes and Recreational
Vehicles, IBR approved for § 3280.604(b).
(3) ANSI/NSF 61-2001, Drinking Water System Components-Health Effects, IBR approved for §
3280.604(b).
(dd) Resources, Applications, Designs, & Controls (RADCO), 3220 East 59th Street, Long Beach, CA 90805,
telephone number 562-272-7231, fax number 562-529-7513, Web site: http://www.radcoinc.com.
(1) RADCO DS-010-91, Decorative Gas Appliances for Installation in Solid Fuel Burning Fireplaces, May
1991, IBR approved for § 3280.703.
(2) [Reserved]

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Manufactured Home Construction and Safety Standards

24 CFR 3280.4(ee)

(ee) Society of Automotive Engineers (SAE), 400 Commonwealth Drive, Warrendale, PA 15096, telephone
number 724-776-0790, Web site: http://www.sae.org/.
(1) SAE-J533b-1992, Flares for Tubing, IBR approved for §§ 3280.703 and 3280.705(f).
(2) [Reserved]
(ff) Steel Joist Institute (SJI), 234 West Cheves Street, Florence, SC 29501, telephone number 843-407-4091,
Web site: http://steeljoist.org.
(1) Standard Specifications Load Tables and Weight Tables for Steel Joists and Joist Girders, SJI 1994,
Fortieth Edition, IBR approved for § 3280.304(b).
(2) [Reserved]
(gg) Truss Plate Institute (TPI), 218 North Lee Street, Suite 312, Alexandria, VA 22314, telephone number
703-683-1010, fax number 866-501-4012, Web site: http://www.tpinst.org/index.html.
(1) TPI-85, Design Specifications for Metal Plate and Wood Connected Trusses, IBR approved for §
3280.304(b).
(2) [Reserved]
(hh) Underwriters' Laboratories, Inc. (UL), 333 Pfingsten Road, Northbrook, IL 60062, telephone number
847-272-8800, fax number 847-509-6257, Web site: http://www.ul.com.
(1) UL 94-1996, with 2001 revisions, Test for Flammability of Plastic Materials for Parts in Devices and
Appliances, Fifth Edition, IBR approved for § 3280.715(e).
(2) UL 103-1995, with 1999 revisions, Factory-Built Chimneys for Residential Type and Building Heating
Appliances, Ninth Edition, IBR approved for § 3280.703.
(3) UL 109-1997, with 2001 revisions, Tube Fittings for Flammable and Combustible Fluids, Refrigeration
Service, and Marine Use, Sixth Edition, IBR approved for § 3280.703.
(4) UL 127-1996, with 1999 revisions, Factory-Built Fireplaces, Seventh Edition, IBR approved for §
3280.703.
(5) UL 174-1996, with 1997 revisions, Household Electric Storage Tank Water Heaters, Tenth Edition, IBR
approved for § 3280.703.
(6) UL 181 Factory-Made Air Ducts and Air Connectors, Ninth Edition, April 4, 1996, with revisions
through May 15, 2003, IBR approved for §§ 3280.702, 3280.703 and 3280.715(a).
(7) UL 181A, 1994, with 1998 revisions, Standard for Safety Closure Systems for use with Rigid Air Ducts
and Air Connectors, Second Edition, IBR approved for §§ 3280.703 and 3280.715(c).
(8) UL 181B, 1995, with 1998 revisions, Standard for Safety Closure Systems for use with Flexible Air
Ducts and Air Connectors, First Edition, IBR approved for §§ 3280.703 and 3280.715(c).
(9) UL 217, Single and Multiple Station Smoke Alarms, Fifth Edition, dated January 4, 1999, IBR approved
for §§ 3280.208(a) and 3280.211(a).
(10) UL 268, Smoke Detectors for Fire Protective Signaling Systems, Fourth Edition, dated January 4,
1999, IBR approved for § 3280.208(a).

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24 CFR 3280.4(hh)(11)

(11) UL 307A-1995, Liquid Fuel-Burning Heating Appliances for Manufactured Homes and Recreational
Vehicles, Seventh Edition, with 1997 revisions, IBR approved for §§ 3280.703 and 3280.707(f).
(12) UL 307B-1995, Gas Burning Heating Appliances for Manufactured Homes and Recreational Vehicles,
Fourth Edition, with 1998 revisions, IBR approved for § 3280.703.
(13) UL 311, 1994, with 1998 revisions, Roof Jacks for Manufactured Homes and Recreational Vehicles,
Eighth Edition, IBR approved for § 3280.703.
(14) UL 441, 1996 with 1999 revisions, Gas Vents, Ninth Edition, IBR approved for § 3280.703.
(15) UL 569, 1995 with 2001 revisions, Pigtails and Flexible Hose Connectors for LP-Gas, Seventh Edition,
IBR approved for §§ 3280.703 and 3280.705(k).
(16) UL 737, 1996, Fireplace Stoves, Eight Edition, with 2000 revisions, IBR approved for § 3280.703.
(17) UL 923 Microwave Cooking Appliances, Fifth Edition, May 23, 2002, IBR approved for § 3280.204(c).
(18) UL 1042-1994, Electric Baseboard Heating Equipment, Fourth Edition, with 1998 revisions, IBR
approved for § 3280.703.
(19) UL 1096, 1986, Electric Central Air Heating Equipment, Fourth Edition with revisions July 16, 1986,
and January 30, 1988, IBR approved for § 3280.703.
(20) UL 1482, 1996, with 2000 revisions, Solid-Fuel Type Room Heaters, Fifth Edition, IBR approved for §
3280.703.
(21) UL 1995, 1995, Heating and Cooling Equipment, Second Edition, with 1999 revisions, IBR approved
for § 3280.703.
(22) UL 2021-1997. Fixed and Location-Dedicated Electric Room Heaters, Second Edition, with 1998
revisions, IBR approved for § 3280.703.
(23) ANSI/UL 2034-2016, Standard for Single and Multiple Station Carbon Monoxide Alarms, Third Edition,
dated February 28, 2008 (including revisions through May 11, 2016), IBR approved for § 3280.211(a).
(ii) Underwriters' Laboratories of Canada (ULC), 7 Underwriters Road, Toronto, Ontario, Canada M1 R 3A9,
telephone number 866-937-3852, fax number 416-757-8727, Web site: http://www.ul.com/canada/eng/
pages/.
(1) CAN/ULC S102.2-M88, Standard Method of Test for Surface Burning Characteristics of Floor
Coverings and Miscellaneous Materials and Assemblies, Fourth Edition, April 1988, IBR approved for
§ 3280.207(b).
(2) [Reserved]
(jj) Window and Door Manufacturers Association (WDMA) (Previously known as the National Wood Window
and Door Association, (NWWDA)), 2025 M Street, NW., Suite 800, Washington, DC 20036-3309, telephone
number 202-367-1157, Web site: https://www.wdma.com.
(1) NWWDA I.S.4-81, Water Repellent Preservative Non-Pressure Treatment for Millwork, IBR approved
for § 3280.405(b).
(2) [Reserved]
[78 FR 73976, Dec. 9, 2013, as amended at 79 FR 31863, June 3, 2014; 85 FR 5566, Jan. 31, 2020; 86 FR 2516, Jan. 12, 2021]
24 CFR 3280.4(jj)(2) (enhanced display)

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24 CFR 3280.5

§ 3280.5 Data plate.
Each manufactured home shall bear a data plate affixed in a permanent manner near the main electrical panel or
other readily accessible and visible location. Each data plate shall be made of material what will receive typed
information as well as preprinted information, and which can be cleaned of ordinary smudges or household dirt
without removing information contained on the data plate; or the data plate shall be covered in a permanent manner
with materials that will make it possible to clean the data plate of ordinary dirt and smudges without obscuring the
information. Each data plate shall contain not less than the following information:
(a) The name and address of the manufacturing plant in which the manufactured home was manufactured.
(b) The serial number and model designation of the unit, and the date the unit was manufactured.
(c) The applicable statement:
This manufactured home is designed to comply with the Federal Manufactured Home Construction and Safety
Standards in force at the time of manufacture.or
This manufactured home has been substantially completed in accordance with an approved design and has
been inspected (except for the components specifically identified in the instructions for completion on-site) in
accordance with the Federal Manufactured Home Construction and Safety Standards and the requirements of
the Department of Housing and Urban Development (HUD) in effect on the date of manufacture.
(d) The applicable statement:
This manufactured home IS designed to accommodate the additional loads imposed by the attachment
of an attached accessory building or structure in accordance with the manufacturer installation
instructions. The additional loads are in accordance with the design load(s) identified on this Data Plate;
or
This manufactured home IS NOT designed to accommodate the additional loads imposed by the
attachment of an attached accessory building or structure in accordance with the manufacturer
installation instructions.
(e) A list of the certification label(s) number(s) that are affixed to each transportable manufactured section
under § 3280.8.
(f) A list of major factory-installed equipment, including the manufacturer's name and the model designation
of each appliance.
(g) Reference to the roof load zone and wind load zone for which the home is designed and duplicates of the
maps as set forth in § 3280.305(c). This information may be combined with the heating/cooling
certificate and insulation zone map required by §§ 3280.510 and 3280.511. The Wind Zone Map on the
Data Plate shall also contain the statement:
This home has not been designed for the higher wind pressures and anchoring provisions required for ocean/
coastal areas and should not be located within 1500′ of the coastline in Wind Zones II and III, unless the home
and its anchoring and foundation system have been designed for the increased requirements specified for
Exposure D in ANSI/ASCE 7-88.
(h) The statement:

24 CFR 3280.5(h) (enhanced display)

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24 CFR 3280.5(i)

This home has - has not - (appropriate blank to be checked by manufacturer) been equipped with storm
shutters or other protective coverings for windows and exterior door openings. For homes designed to be
located in Wind Zones II and III, which have not been provided with shutters or equivalent covering devices, it is
strongly recommended that the home be made ready to be equipped with these devices in accordance with the
method recommended in the manufacturers printed instructions.
(i)

The statement: “Design Approval by”, followed by the name of the agency that approved the design.

(j)

The statement: The manufacturer certifies this home is compliant with the Title VI, Toxic Substances
Control Act.

[59 FR 2469, Jan. 14, 1994, as amended at 80 FR 53727, Sept. 8, 2015; 85 FR 5566, Jan. 31, 2020; 86 FR 2516, Jan. 12, 2021]

§ 3280.6 Serial number.
(a) A manufactured home serial number which will identify the manufacturer and the state in which the
manufactured home is manufactured, must be stamped into the foremost cross member. Letters and
numbers must be 3⁄8 inch minimum in height. Numbers must not be stamped into hitch assembly or
drawbar.

§ 3280.7 Excluded structures.
Certain structures may be excluded from these Standards as modular homes under 24 CFR 3282.12.
[52 FR 4581, Feb. 12, 1987]

§ 3280.8 Waivers.
(a) Where any material piece of equipment, or system which does not meet precise requirements or
specifications set out in the standard is shown, to the satisfaction of the Secretary, to meet an equivalent
level of performance, the Secretary may waive the specifications set out in the Standard for that material,
piece of equipment, or system.
(b) Where the Secretary is considering issuing a waiver to a Standard, the proposed waiver shall be published
in the FEDERAL REGISTER for public comment, unless the Secretary, for good cause, finds that notice is
impractical, unnecessary or contrary to the public interest, and incorporates into the waiver that finding
and a brief statement of the reasons therefor.
(c) Each proposed and final waiver shall include:
(1) A statement of the nature of the waiver; and
(2) Identification of the particular standard affected.
(d) All waivers shall be published in the FEDERAL REGISTER and shall state their effective date. Where a waiver
has been issued, the requirements of the Federal Standard to which the waiver relates may be met either
by meeting the specifications set out in the Standard or by meeting the requirements of the waiver
published in the FEDERAL REGISTER.
[58 FR 55003, Oct. 25, 1993]

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24 CFR 3280.9

§ 3280.9 Interpretative bulletins.
Interpretative bulletins may be issued for the following purposes:
(a) To clarify the meaning of the Standard; and
(b) To assist in the enforcement of the Standard.
[58 FR 55003, Oct. 25, 1993]

§ 3280.10 Use of alternative construction.
Requests for alternative construction can be made pursuant to 24 CFR 3282.14 of this chapter.
[58 FR 55003, Oct. 25, 1993]

§ 3280.11 Certification label.
(a) A permanent label shall be affixed to each transportable section of each manufactured home for sale or
lease in the United States. This label shall be separate and distinct from the data plate which the
manufacturer is required to provide under § 3280.5 of the standards.
(b) The label shall be approximately 2 in. by 4 in. in size and shall be permanently attached to the
manufactured home by means of 4 blind rivets, drive screws, or other means that render it difficult to
remove without defacing it. It shall be etched on 0.32 in. thick aluminum plate. The label number shall be
etched or stamped with a 3 letter designation which identifies the production inspection primary
inspection agency and which the Secretary shall assign. Each label shall be marked with a 6 digit number
which the label supplier shall furnish. The labels shall be stamped with numbers sequentially.
(c) The label shall read as follows:
As evidenced by this label No. ABC 000001, the manufacturer certifies to the best of the manufacturer's
knowledge and belief that this manufactured home has been inspected in accordance with the requirements of
the Department of Housing and Urban Development and is constructed in conformance with the Federal
manufactured home construction and safety standards in effect on the date of manufacture. See date plate.
(d) The label must be located at the taillight end of each transportable section of the manufactured home
approximately 1 foot up from the floor and 1 foot in from the road side, or as near that location on a
permanent part of the exterior of the manufactured home section as practicable. The road side is the right
side of the manufactured home when one views the manufactured home from the tow bar end of the
manufactured home. If locating the label on the taillight end of a transportable section will prevent the
label from being visible after the manufactured home section is installed at the installation site, the label
must be installed on a permanent part of the exterior of the manufactured home section, in a visible
location as specified in the approved design.
[42 FR 960, Jan. 4, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 47553, Dec. 15, 1987. Redesignated
and amended at 58 FR 55003, Oct. 25, 1993; 86 FR 2517, Jan. 12, 2021]

Subpart B - Planning Considerations

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24 CFR 3280.101

§ 3280.101 Scope.
Subpart B states the planning requirements in manufactured homes. The intent of this subpart is to assure the
adequacy of architectural planning considerations which assist in determining a safe and healthful environment.

§ 3280.102 Definitions.
(a) Gross floor area means all space, wall to wall, including recessed entries not to exceed 5 sq. ft. and areas
under built-in vanities and similar furniture. Where the ceiling height is less than that specified in §
3280.104, the floor area under such ceilings shall not be included. Floor area of closets shall not be
included in the gross floor area.
(b) Habitable room means a room or enclosed floor space arranged for living, eating, food preparation, or
sleeping purposes not including bathrooms, foyers, hallways, and other accessory floor space.
(c) Laundry area means an area containing or designed to contain a laundry tray, clothes washer and/or
clothes dryer.

§ 3280.103 Light and ventilation.
(a) Lighting. Each habitable room shall be provided with exterior windows and/or doors having a total glazed
area of not less than 8 percent of the gross floor area.
(1) Kitchens, bathrooms, toilet compartments, laundry areas, and utility rooms may be provided with
artificial light in place of windows.
(2) Rooms and areas may be combined for the purpose of providing the required natural lighting
provided that at least one half of the common wall area is open and unobstructed, and the open area
is at least equal to 10 percent of the combined floor area or 25 square feet whichever is greater.
(b) Whole-house ventilation. Each manufactured home must be provided with whole-house ventilation having
a minimum capacity of 0.035 ft3/min/ft2 of interior floor space or its hourly average equivalent. This
ventilation capacity must be in addition to any openable window area. In no case shall the installed
ventilation capacity of the system be less than 50 cfm. The following criteria must be adhered to:
(1) The ventilation capacity must be provided by a mechanical system or a combination passive and
mechanical system. The ventilation system or provisions for ventilation must not create a positive
pressure in Uo Value Zone 2 and Zone 3 or a negative pressure condition in Uo Value Zone 1.
Mechanical systems must be balanced. Combination passive and mechanical systems must have
adequately sized inlets or exhaust to release any unbalanced pressure. Temporary pressure
imbalances due to gusting or high winds are permitted.
(2) The ventilation system or provisions for ventilation must exchange air directly with the exterior of the
home, except the ventilation system, or provisions for ventilation must not draw or expel air with the
space underneath the home. The ventilation system or provisions for ventilation must not draw or
expel air into the floor, wall, or ceiling/roof systems, even if those systems are vented. The ventilation
system must be designed to ensure that outside air is distributed to all bedrooms and main living
areas. The combined use of undercut doors or transom grills connecting those areas to the room
where the mechanical system is located is deemed to meet this requirement.

24 CFR 3280.103(b)(2) (enhanced display)

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24 CFR 3280.103(b)(3)

(3) The ventilation system or a portion of the system is permitted to be integral with the home's heating
or cooling system. The system must be capable of operating independently of the heating or cooling
modes. A ventilation system that is integral with the heating or cooling system is to be listed as part
of the heating and cooling system or listed as suitable for use with that system.
(4) A mechanical ventilation system, or mechanical portion thereof, must be provided with a manual
control, and must be permitted to be provided with automatic timers or humidistats.
(5) A whole-house ventilation label must be attached to the whole-house ventilation control, must be
permanent, and must state: “WHOLE-HOUSE VENTILATION”.
(6) Instructions for correctly operating and maintaining whole-house ventilation systems must be
included with the homeowner's manual. The instructions must encourage occupants to operate
these systems whenever the home is occupied, and must refer to the labeled whole-house
ventilation control.
(c) Additional ventilation.
(1) At least half of the minimum required glazed area in paragraph (a) of this section shall be openable
directly to the outside of the manufactured home for unobstructed ventilation. These same
ventilation requirements apply to rooms combined in accordance with § 3280.103(a)(2).
(2) Kitchens shall be provided with a mechanical ventilation system that is capable of exhausting 100
cfm to the outside of the home. The exhaust fan shall be located as close as possible to the range or
cook top, but in no case farther than 10 feet horizontally from the range or cook top.
(3) Each bathroom and separate toilet compartment shall be provided with a mechanical ventilation
system capable of exhausting 50 cfm to the outside of the home. A separate toilet compartment
may be provided with 1.5 square feet of openable glazed area in place of mechanical ventilation,
except in Uo value Zone 3.
(d) Optional ventilation provisions. As an option to complying with the provisions of paragraphs (b) and (c) of
this section, ventilation systems complying with ANSI/ASHRAE Standard 62.2 (incorporated by reference,
see § 3280.4) may be used.
[58 FR 55003, Oct. 25, 1993, as amended at 70 FR 72042, Nov. 30, 2005; 86 FR 2517, Jan. 12, 2021]

§ 3280.104 Ceiling heights.
(a) Every habitable room and bathroom shall have a minimum ceiling height of not less than 7 feet, 0 inches
for a minimum of 50 percent of the room's floor area. The remaining area may have a ceiling with a
minimum height of 5 feet, 0 inches. Minimum height under dropped ducts, beams, etc. shall be 6 feet, 4
inches.
(b) Hallways and foyers shall have a minimum ceiling height of 6 feet, 6 inches.

§ 3280.105 Exit facilities; exterior doors.
(a) Number and location of exterior doors. Manufactured homes shall have a minimum of two exterior doors
located remote from each other.
(1) Required egress doors shall not be located in rooms where a lockable interior door must be used in
order to exit.
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24 CFR 3280.105(a)(2)

(2) In order for exit doors to be considered remote from each other, they must comply with all of the
following:
(i)

Both of the required doors must not be in the same room or in a group of rooms which are not
defined by fixed walls.

(ii) Single wide units. Doors may not be less than 12 ft. c-c from each other as measured in any
straight line direction regardless of the length of path of travel between doors.
(iii) Double wide units. Doors may not be less than 20 ft. c-c from each other as measured in any
straight line direction regardless of the length of path of travel between doors.
(iv) One of the required exit doors must be accessible from the doorway of each bedroom without
traveling more than 35 feet. The travel distance to the exit door must be measured on the floor
or other walking surface along the center-line of the natural and unobstructed path of travel
starting at the center of the bedroom door, curving around any corners or permanent
obstructions with a one-foot clearance from, and ending at, the center of the exit door.
(b) Door design and construction.
(1) Exterior swinging doors shall be constructed in accordance with § 3280.405 the “Standard for
Swinging Exterior Passage Doors for Use in Manufactured Homes”. Exterior sliding glass doors shall
be constructed in accordance with § 3280.403 the “Standard for Windows and Sliding Glass Doors
Used in Manufactured Homes”.
(2) All exterior swinging doors must provide a minimum 28-inch wide × 74-inch high clear opening. Door
seals are permitted to reduce the opening, either vertically or horizontally, a maximum of one inch.
All exterior sliding glass doors must provide a minimum 28-inch wide × 72-inch high clear opening.
(3) Each swinging exterior door other than screen or storm doors shall have a key-operated lock that has
a deadlocking latch or a key-operated dead bolt with a passage latch. Locks shall not require the use
of a key for operation from the inside.
(4) All exterior doors, including storm and screen doors, opening outward shall be provided with a safety
door check.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 50 FR 9269, Mar. 7, 1985; 78 FR 73981,
Dec. 9, 2013]

§ 3280.106 Exit facilities; egress windows and devices.
(a) Every room designed expressly for sleeping purposes, unless it has an exit door (see § 3280.105), shall
have at least one outside window or approved exit device which meets the requirements of § 3280.404,
the “Standard for Egress Windows and Devices for Use in Manufactured Homes.”
(b) The bottom of the window opening shall not be more than 36 inches above the floor.
(c) Locks, latches, operating handles, tabs, and any other window screen or storm window devices which
need to be operated in order to permit exiting, shall not be located in excess of 54 inches from the
finished floor.
(d) Integral rolled-in screens shall not be permitted in an egress window unless the window is of the hingedtype.
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24 CFR 3280.107

[49 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 49 FR 36086, Sept. 14, 1984; 52 FR 4581,
Feb. 12, 1987]

§ 3280.107 Interior privacy.
Bathroom and toilet compartment doors shall be equipped with a privacy lock.

§ 3280.108 Interior passage.
(a) Interior doors having passage hardware without a privacy lock, or with a privacy lock not engaged, shall
open from either side by a single movement of the hardware mechanism in any direction.
(b) Each manufactured home interior door, when provided with a privacy lock, shall have a privacy lock that
has an emergency release on the outside to permit entry when the lock has been locked by a locking knob,
lever, button, or other locking device on the inside.
(c) All interior swinging doors must have a minimum clear opening of 27 inches except doors to toilet
compartments in single-section homes (see § 3280.111(b)), and doors to closets and pantries.
[40 FR 58752, Dec. 18, 1975, as amended at 86 FR 2517, Jan. 12, 2021]

§ 3280.109 Room requirements.
(a) Every manufactured home shall have at least one living area with not less than 150 sq. ft. of gross floor
area.
(b) Rooms designed for sleeping purposes shall have a minimum gross square foot floor area as follows:
(1) All bedrooms shall have at least 50 sq. ft. of floor area.
(2) Bedrooms designed for two or more people shall have 70 sq. ft. of floor area plus 50 sq. ft. for each
person in excess of two.
(c) Every room designed for sleeping purposes shall have accessible clothes hanging space with a minimum
inside depth of 22 inches and shall be equipped with a rod and shelf.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, and further redesignated at 58 FR 55004, Oct. 25, 1993]

§ 3280.110 Minimum room dimensions.
The gross floor area required by § 3280.110 (a) and (b) shall have no clear horizontal dimension less than 5 feet
except as permitted by § 3280.102(a).
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, and further redesignated at 58 FR 55004, Oct. 25, 1993]

§ 3280.111 Toilet compartments.
(a) Each toilet compartment must be a minimum of 30 inches wide, except, when the toilet is located
adjacent to the short dimension of the tub, the distance from the tub, to the center line of the toilet must
not be less than 12 inches. At least 21 inches of clear space must be provided in front of each toilet.

24 CFR 3280.111(a) (enhanced display)

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24 CFR 3280.111(b)

(b) All bathroom passage doors in single-section homes must have a minimum clear opening width of 23
inches, and bathroom passage doors in multi-section homes must have a minimum clear opening width
of 27 inches.
[86 FR 2517, Jan. 12, 2021]

§ 3280.112 Hallways.
Hallways shall have a minimum horizontal dimension of 28 inches measured from the interior finished surface to
the interior finished surface of the opposite wall. When appliances are installed in a laundry area, the measurement
shall be from the front of the appliance to the opposite finished interior surface. When appliances are not installed
and a laundry area is provided, the area shall have a minimum clear depth of 27 inches in addition to the 28 inches
required for passage. In addition, a notice of the available clearance for washer/dryer units shall be posted in the
laundry area. Minor protrusions into the minimum hallway width by doorknobs, trim, smoke alarms or light fixtures
are permitted.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, and further redesignated at 58 FR 55004, Oct. 25, 1993;
67 FR 12817, Mar. 19, 2002]

§ 3280.113 Glass and glazed openings.
(a) Windows and sliding glass doors. All windows and sliding glass doors shall meet the requirements of §
3280.403 the “Standard for Windows and Sliding Glass Doors Used in Manufactured Homes”.
(b) Required glazed openings shall be permitted to face into a roofed porch where the porch abuts a street,
yard, or court and the longer side of the porch is at least 65 percent open and unobstructed and the
ceiling height is not less than 7 feet.
(c) Hazardous locations requiring safety glazing. Except as provided in paragraph (d) of this section, the
following locations and areas require the use of safety glazing conforming to the requirements of
paragraph (c) of this section:
(1) Glazing in all entrance or exit doors;
(2) Glazing in fixed and sliding panels of sliding glass doors;
(3) Glazing in storm-type doors;
(4) Glazing in unframed side-hinged swinging doors;
(5) Glazing in doors and fixed panels less than 60 inches above the room floor level that enclose
bathtubs, showers, hydromassage tubs, hot tubs, whirlpools, saunas;
(6) Glazing within 12 inches horizontally, as measured from the edge of the door in the closed position,
and 60 inches vertically as measured from the room floor level, adjacent to and in the same plane of
a door;
(7) Glazing within 36 inches of an interior room walking surface when the glazing meets all of the
following:
(i)

Individual glazed panels exceed 9 square feet in area in an exposed surface area;

(ii) The bottom edge of the exposed glazing is less than 19 inches above the room floor level; and
24 CFR 3280.113(c)(7)(ii) (enhanced display)

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24 CFR 3280.113(c)(7)(iii)

(iii) The top edge of the exposed glazing is greater than 36 inches above the room floor level.
(8) Glazing in rails and guardrails; and
(9) Glazing in unbacked mirrored wardrobe doors (i.e., mirrors that are not secured to a backing that is
capable of being the door itself).
(d) Safety glazing material is considered to be any glazing material capable of meeting the requirements of
Consumer Product Safety Commission 16 CFR part 1201, or Standard for Safety Glazing Materials used in
Buildings - Safety Performance Specifications and Methods of Test, ANSI Z97.1-2004 (incorporated by
reference, see § 3280.4).
(e) Glazing in the following locations is not required to meet the requirements in paragraph (b) of this section:
(1) Openings in doors through which a 3-inch sphere is unable to pass;
(2) Leaded and decorative glazed panels;
(3) Glazing in jalousie-type doors;
(4) Glazing as described in paragraph (b)(6) of this section when an intervening wall or other permanent
barrier exists between the door and the glazing;
(5) Glazing as described in paragraph (b)(7) of this section when a protective bar or member is installed
horizontally between 34 inches and 38 inches above the room floor level, as long as the bar or
member is a minimum of 11⁄2 inches in height and capable of resisting a horizontal load of 50
pounds per lineal foot; and
(6) Mirrors mounted on a flush door surface or solid wall surface.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4581, Feb. 12, 1987. Redesignated
at 58 FR 55004, Oct. 25, 1993; 78 FR 73981, Dec. 9, 2013; 86 FR 2517, Jan. 12, 2021]

§ 3280.114 Stairways.
(a) Stairways (1) General. These minimum standards apply to stairways that are designed and constructed as part of
the factory-completed transportable section(s) of a manufactured home, such as interior stairways
for multi-level or multi-story homes or external stairways for multi-level construction features that
are designed and constructed in the factory on a transportable section and integral to the access
and egress needs within the transportable section(s) of a home. These standards do not apply to
exterior stairways that are built at the home site or stairways to basement areas that are not
designed and built as part of a transportable section of a manufactured home.
(2) Width. Stairways must not be less than 36 inches in clear width at all points above permitted handrail
height and below the required headroom height. Handrails must not project more than 41⁄2 inches on
either side of the stairway and the minimum clear width of the stairway at and below the handrail
height, including treads and landings, must not be less than 311⁄2 inches where a handrail is installed
on one side and 27 inches where handrails are provided on both sides.
(3) Stair treads and risers -

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(i)

24 CFR 3280.114(a)(3)(i)

Riser height and tread depth. The maximum riser height must not exceed 81⁄4 inches and the
minimum tread depth must not be less than 9 inches. The riser height must be measured
vertically between leading edges of the adjacent treads. The tread depth must be measured
horizontally between the vertical planes of the foremost projection of adjacent treads and at a
right angle to the tread's leading edge. The walking surface of treads and landings of a stairway
must be sloped no steeper than one unit vertical in 48 units horizontal (a 2-percent slope). The
greatest riser height within any flight of stairs must not exceed the smallest by more than 3⁄8
inch. The greatest tread depth within any flight of stairs must not exceed the smallest by more
than 3⁄8 inch.

(ii) Profile. The radius of curvature at the leading edge of the tread must not be greater than 9⁄16
inch. A nosing not less than 3⁄4 inch but not more than 11⁄4 inches shall be provided on
stairways with solid risers. The greatest nosing projection must not exceed the smallest nosing
projection by more than 3⁄4 inch between two stories, including the nosing at the level of floors
and landings. Beveling of nosing must not exceed 1⁄2 inch. Risers must be vertical or sloped
from the underside of the leading edge of the tread above at an angle not more than 30 degrees
from the vertical. Open risers are permitted, provided that the opening between treads does not
permit the passage of a 4-inch diameter sphere. A nosing is not required where the tread depth
is a minimum of 11 inches. The opening between adjacent treads is not limited on stairs with a
total rise of 30 inches or less.
(4) Headroom. The minimum headroom in all parts of the stairway must not be less than 6 feet 8 inches,
measured vertically from the sloped plane adjoining the tread nosing or from the floor surface of the
landing or platform.
(5) Winders (winding stairways). Winders are permitted, provided that the width of the tread at a point
not more than 12 inches from the side where the treads are narrower is not less than 10 inches and
the minimum width of any tread is not less than 6 inches. Within any flight of stairs, the greatest
winder tread depth at the 12-inch walk line must not exceed the smallest by more than 3⁄8 inch. The
continuous handrail required by paragraph (c)(3) of this section must be located on the side where
the tread is narrower.
(6) Spiral stairways. Spiral stairways are permitted provided the minimum width is a minimum 26 inches
with each tread having 71⁄2 inch minimum tread width at 12 inches from the narrow edge. All treads
must be identical, and the rise must be no more than 91⁄2 inches. Minimum headroom of 6 feet, 6
inches must be provided.
(7) Circular stairways. Circular stairways must have a tread depth at a point not more than 12 inches
from the side where the treads are narrower of not less than 11 inches and the minimum depth of
any tread must not be less than 6 inches. Tread depth at any walking line, measured a consistent
distance from a side of the stairway, must be uniform as specified in paragraph (a)(2)(i) of this
section.
(b) Landings. Every landing must have a minimum dimension of 36 inches measured in the direction of travel.
Landings must be located as follows:
(1) There must be a floor or landing at the top and bottom of each stairway, except at the top of an
interior flight of basement stairs, provided a door does not swing over the stairs.

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24 CFR 3280.114(b)(2)

(2) A landing or floor must be located on each side of an interior doorway and exterior doorway, to the
extent the external stairway is designed by the home manufacturer and constructed in the factory,
and the width of each landing must not be less than the door it serves. The maximum threshold
height above the floor or landing must be 11⁄2-inches.
(c) Handrails (1) General. A minimum of one handrail meeting the requirements of this section must be installed on all
stairways consisting of four or more risers. Handrails must be securely attached to structural
framing members. A minimum space of 11⁄2 inches must be provided between the adjoining wall
surface and the handrail.
(2) Handrail height. Handrails must be installed between 34 inches and 38 inches measured vertically
from the leading edge of the stairway treads except that handrails installed up to 42 inches high
must be permitted if serving as the upper rails of guards required by paragraph (d) of this section.
(3) Continuity. Required handrails must be continuous from a point directly above the leading edge of the
lowest stair tread to a point directly above the leading edge of the landing or floor surface at the top
of the stairway. If the handrail is extended at the top of the stairway flight, the extension must
parallel the floor or landing surface and must be at the same height as the handrail above the leading
edges of the treads. If the handrail is extended at the base of the stair, it must continue to slope
parallel to the stair flight for a distance of one tread depth, measured horizontally, before being
terminated or returned or extended horizontally. The ends of handrails must return into a wall or
terminate in a safety terminal or newel post.
(4) Graspability. Required handrails must, if circular in cross section, have a minimum 11⁄4-inch and a
maximum 2-inch diameter dimension. Handrails with a noncircular cross section must have a
perimeter dimension of at least 4 inches and not more than 61⁄4 inches (with a maximum crosssection dimension of not more than 21⁄4 inches). The handgrip portion of the handrail must have a
smooth surface. Edges must have a minimum 1⁄8-inch radius. Handrails must be continuously
graspable along their entire length except that brackets or balusters are not considered obstructions
to graspability if they do not project horizontally beyond the sides of the handrail within 11⁄2 inches of
the bottom of the handrail.
(5) Required resistance of handrails. Handrails must be designed to resist a load of 20 lb./ft applied in
any direction at the top and to transfer this load through the supports to the structure. All handrails
must be able to resist a single concentrated load of 200 lbs., applied in any direction at any point
along the top, and have attachment devices and supporting structures to transfer this loading to
appropriate structural elements of the building. This load is not required to be assumed to act
concurrently with the loads specified in this section.
(d) Guards.
(1) Porches, balconies, or raised floor surfaces located more than 30 inches above the floor or grade
below must have guards not less than 36 inches in height. Open sides of stairs with a total rise of
more than 30 inches above the floor or grade below must have guards not less than 34 inches in
height measured vertically from the nosing of the treads. Balconies and porches on the second floor
or higher must have guards a minimum of 42 inches in height.
(2) Required guards on open sides of stairways, raised floor areas, balconies, and porches must have
intermediate rails or ornamental closures that do not allow passage of a sphere 4 inches in diameter.
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(i)

24 CFR 3280.114(d)(2)(i)

The triangular openings formed by the riser, tread and bottom rail of a guard at the open side of
the stairway must be of such a size that a sphere of 6 inches cannot pass through.

(ii) Guard systems must be designed to resist a load of 20 lb./ft applied in any direction at the top
and to transfer this load through the supports to the structure. All guard systems must be able
to resist a single concentrated load of 200 lb., applied in any direction at any point along the top
and have attachment devices and supporting structures to transfer this loading to appropriate
structural elements of the building. This load is not required to be assumed to act concurrently
with the loads specified in this section.
(e) Stairway illumination. All interior and exterior stairways must be provided with a means to illuminate the
stairways, including the landings and treads.
(1) Interior stairways must be provided with an artificial light source located in the immediate vicinity of
each landing of the stairway. For interior stairs, the artificial light sources must be capable of
illuminating treads and landings to levels not less than one (1) foot-candle measured at the center of
treads and landings. The control and activation of the required interior stairway lighting must be
accessible at the top and bottom of each stairway without traversing any steps.
(2) Exterior stairways designed by the home manufacturer and constructed in the factory must be
provided with an artificial light source located in the immediate vicinity of the top landing of the
stairway. An artificial light source is not required at the top and bottom landing, provided an artificial
light source is located directly over each stairway section. The illumination of exterior stairways
must be controlled from inside the home.
[86 FR 2517, Jan. 12, 2021]

Subpart C - Fire Safety
Source: 49 FR 32008, Aug. 9, 1984, unless otherwise noted.

§ 3280.201 Scope.
The purpose of this subpart is to set forth requirements that will assure reasonable fire safety to the occupants by
reducing fire hazards and by providing measures for early detection.

§ 3280.202 Definitions.
The following definitions are applicable to subparts C, H, and I of the Standards:
Combustible material: Any material not meeting the definition of limited-combustible or non-combustible
material.
Flame-spread rating: The measurement of the propagation of flame on the surface of materials or their
assemblies as determined by recognized standard tests conducted as required by this subpart.
Interior finish: The surface material of walls, fixed or movable partitions, ceilings, columns, and other exposed
interior surfaces affixed to the home's structure including any materials such as paint or wallpaper and
the substrate to which they are applied. Interior finish does not include:

24 CFR 3280.202 “Interior finish:” (enhanced display)

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24 CFR 3280.202 “Interior finish:” (1)

(1) Trim and sealant 2 inches or less in width adjacent to the cooking range and in furnace and water
heater spaces provided it is installed in accordance with the requirements of § 3280.203(b)(3) or (4),
and trim 6 inches or less in width in all other areas;
(2) Windows and frames;
(3) Single doors and frames and a series of doors and frames not exceeding 5 feet in width;
(4) Skylights and frames;
(5) Casings around doors, windows, and skylights not exceeding 4 inches in width;
(6) Furnishings which are not permanently affixed to the home's structure;
(7) Baseboards not exceeding 6 inches in height;
(8) Light fixtures, cover plates of electrical receptacle outlets, switches, and other devices;
(9) Decorative items attached to walls and partitions (i.e., pictures, decorative objects, etc.) constituting
no more than 10% of the aggregate wall surface area in any room or space not more than 32 square
feet in surface area, whichever is less;
(10) Plastic light diffusers when suspended from a material which meets the interior finish provisions of §
3280.203(b);
(11) Coverings and surfaces of exposed wood beams; and
(12) Decorative items including the following:
(i)

Non-structural beams not exceeding 6 inches in depth and 6 inches in width and spaced not
closer than 4 feet on center;

(ii) Non-structural lattice work;
(iii) Mating and closure molding; and
(iv) Other items not affixed to the home's structure.
Limited combustible: A material meeting:
(1) The definition contained in Chapter 2 of NFPA 220-1995, Standard on Types of Building Construction;
or
(2)

5⁄

16-inch

or thicker gypsum board.

Noncombustible material: A material meeting the definition contained in Chapter 2 of NFPA 220-1995, Standard
on Types of Building Construction.
Smoke alarm: An alarm device that is responsive to smoke.
Tactile notification appliance: A notification appliance that alerts by the sense of touch or vibration.
[58 FR 55004, Oct. 25, 1993, as amended at 67 FR 12817, Mar. 19, 2002; 70 FR 72042, Nov. 30, 2005]

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24 CFR 3280.203

§ 3280.203 Flame spread limitations and fire protection requirements.
(a) Establishment of flame spread rating. The surface flame spread rating of interior-finish material must not
exceed the value shown in § 3280.203(b) when tested by Standard Test Method for Surface Burning
Characteristics of Building Materials, ASTM E84-01, 2001, or Standard Method of Test of Surface Burning
Characteristics of Building Materials NFPA 255, 1996, except that the surface flame spread rating of
interior-finish materials required by § 3280.203(b)(5) and (6) may be determined by using the Standard
Test Method for Surface Flammability of Materials Using a Radiant Heat Energy Source, ASTM E 162-94.
However, the following materials need not be tested to establish their flame spread rating unless a lower
rating is required by the standards in this part:
(1) Flame-spread rating - 76 to 200.
(i)

.035-inch or thicker high pressure laminated plastic panel countertop;

(ii)

1⁄

4-inch

or thicker unfinished plywood with phenolic or urea glue;

(iii) Unfinished dimension lumber (1-inch or thicker nominal boards);
(iv)

3⁄

8-inch

or thicker unfinished particleboard with phenolic or urea binder;

(v) Natural gum-varnished or latex- or alkyd-painted:
(A)

1⁄

4-inch

or thicker plywood, or

(B)

3⁄

8-inch

or thicker particleboard, or

(C) 1-inch or thicker nominal board;
(vi)

5⁄

16-inch

(vii)

1⁄

4-inch

gypsum board with decorative wallpaper; and

or thicker unfinished hardboard,

(2) Flame-spread rating-25 to 200,
(i)

Painted metal;

(ii) Mineral-base acoustic tile;
(iii)

5⁄

16-inch

or thicker unfinished gypsum wallboard (both latex- or alkyd-painted); and

(iv) Ceramic tile.
(The above-listed material applications do not waive the requirements of § 3280.203(c) or §
3280.204 of this subpart.)
(b) Flame-spread rating requirements.
(1) The interior finish of all walls, columns, and partitions shall not have a flame spread rating exceeding
200 except as otherwise specified herein.
(2) Ceiling interior finish shall not have a flame spread rating exceeding 75.
(3) Walls adjacent to or enclosing a furnace or water heater and ceilings above them shall have an
interior finish with a flame spread rating not exceeding 25. Sealants and other trim materials 2
inches or less in width used to finish adjacent surfaces within these spaces are exempt from this
provision provided that all joints are completely supported by framing members or by materials
having a flame spread rating not exceeding 25.
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24 CFR 3280.203(b)(4)

(4) Exposed interior finishes adjacent to the cooking range shall have a flame spread rating not
exceeding 50, except that backsplashes not exceeding 6 inches in height are exempted. Adjacent
surfaces are the exposed vertical surfaces between the range top height and the overhead cabinets
and/or ceiling and within 6 horizontal inches of the cooking range. (Refer also to § 3280.204(a),
Kitchen Cabinet Protection.) Sealants and other trim materials 2 inches or less in width used to
finish adjacent surfaces are exempt from this provision provided that all joints are completely
supported by a framing member.
(5) Kitchen cabinet doors, countertops, backsplashes, exposed bottoms, and end panels shall have a
flame spread rating not to exceed 200. Cabinet rails, stiles, mullions, and top strips are exempted.
(6) Finish surfaces of plastic bathtubs, shower units, and tub or shower doors shall not exceed a flame
spread rating of 200.
(c) Fire protective requirements.
(1) Materials used to surface the following areas shall be of limited combustible material (e.g., 5⁄16-inch
gypsum board, etc.):
(i)

The exposed wall adjacent to the cooking range (see § 3280.203(b)(4));

(ii) Exposed bottoms and sides of kitchen cabinets as required by § 3280.204;
(iii) Interior walls and ceilings enclosing furnace and/or water heater spaces; and
(iv) Combustible doors which provide interior or exterior access to furnace and/or water heater
spaces. The surface may be interrupted for louvers ventilating the enclosure. However, the
louvers shall not be constructed of a material of greater combustibility than the door itself (e.g.,
plastic louvers on a wooden door).
(2) No burner of a surface cooking unit shall be closer than 12 horizontal inches to a window or an
exterior door with glazing.
[49 FR 32008, Aug. 9, 1984, as amended at 58 FR 55005, Oct. 25, 1993; 70 FR 72042, Nov. 30, 2005]

§ 3280.204 Kitchen cabinet protection.
(a) The bottom and sides of combustible kitchen cabinets over cooking ranges to a horizontal distance of 6
inches from the outside edge of the cooking range shall be protected with at least 5⁄16-inch thick gypsum
board or equivalent limited combustible material. One-inch nominal framing members and trim are
exempted from this requirement. The cabinet area over the cooking range or cooktops shall be protected
by a metal hood (26-gauge sheet metal, or .017 stainless steel, or .024 aluminum, or .020 copper) with not
less than a 3-inch eyebrow projecting horizontally from the front cabinet face. The 5⁄16-inch thick gypsum
board or equivalent material which is above the top of the hood may be supported by the hood. A 3⁄8-inch
enclosed air space shall be provided between the bottom surface of the cabinet and the gypsum board or
equivalent material. The hood shall be at least as wide as the cooking range.
(b) The 3-inch metal eyebrow required by paragraph (a) of this section will project from the front and rear
cabinet faces when there is no adjacent surface behind the range, or the 5⁄16-inch thick gypsum board or
equivalent material shall be extended to cover all exposed rear surfaces of the cabinet.

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24 CFR 3280.204(c)

(c) Alternative compliance. When all exposed surfaces along the bottoms and sides of combustible kitchen
cabinets are protected as described in paragraph (a) of this section, the metal hood, the 5⁄16-inch thick
gypsum board or equivalent material, and the 3⁄8-inch airspace required by paragraph (a) of this section
can be omitted, provided that:
(1) A microwave oven is installed between the cabinet and the range; and
(2) The microwave oven is equivalent in fire protection to the metal range hood required by paragraph (a)
of this section; and
(3) The microwave oven is certified to be in conformance with Microwave Cooking Appliances, UL
923-2002 (incorporated by reference, see § 3280.4).
(d) When a manufactured home is designed for the future installation of a cooking range, the metal hood and
cabinet protection required by paragraph (a) of this section and the wall-surfacing protection behind the
range required by § 3280.203 shall be installed in the factory.
(e) Vertical clearance above cooking top. Ranges shall have a vertical clearance above the cooking top of not
less than 24 inches to the bottom of combustible cabinets.
[49 FR 32008, Aug. 9, 1984, as amended at 78 FR 73982, Dec. 9, 2013]

§ 3280.205 Carpeting.
Carpeting shall not be used in a space or compartment designed to contain only a furnace and/or water heater.
Carpeting may be used in other areas where a furnace or water heater is installed, provided that it is not located
under the furnace or water heater.

§ 3280.206 Fireblocking.
(a) General. Fireblocking must comply with the requirements of this section. The integrity of all fireblocking
materials must be maintained.
(b) Fireblocking materials. Fireblocking must consist of the following materials:
(1) Minimum one inch nominal lumber, 5⁄16 inch thick gypsum board, or equivalent fire resistive
materials; or
(2) Other Listed or Approved Materials;
(c) Fireblocking locations.
(1) Fireblocking must be installed in concealed spaces of stud walls, partitions, and furred spaces at the
floor and ceiling levels. Concealed spaces must not communicate between floor levels. Concealed
spaces must not communicate between a ceiling level and a concealed roof area, or an attic space.
(2) Fireblocking must be installed at the interconnection of a concealed vertical space and a concealed
horizontal space that occurs:
(i)

Between a concealed wall cavity and the ceiling joists above; and

(ii) At soffits, drop ceilings, cover ceilings, and similar locations.

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24 CFR 3280.206(c)(3)

(3) Fireblocking must be installed around the openings for pipes, vents, and other penetrations in walls,
floors, and ceilings of furnace and water heater spaces. Pipes, vents, and other penetrations that
cannot be moved freely within their opening are considered to be fireblocked. Materials used to
fireblock heat producing vent penetrations must be noncombustible or limited combustible types.
[71 FR 72042, Nov. 30, 2005]

§ 3280.207 Requirements for thermal insulating materials.
(a) General. Except for foam plastic materials and as provided in this section, exposed and concealed thermal
insulating materials, including any facings, must be tested in accordance with NFPA 255-96, Standard
Method of Test of Surface Burning Characteristics of Building Materials (incorporated by reference, see §
3280.4) and must have a flame spread index of 25 or less and a smoke developed index of 450 or less.
The flame spread and smoke developed limitations do not apply to:
(1) Coverings and facings of insulation batts or blankets installed in concealed spaces when the facings
are in substantial contact with the unexposed surface of wall, floor, or ceiling finish; or
(2) Cellulose loose-fill insulation that complies with paragraph (b) of this section.
(b) Loose-fill insulation.
(1) Cellulose loose-fill insulation that is not spray-applied or self-supporting must comply with, and each
package must be labeled in accordance with the Consumer Product Safety Commission
requirements in 16 CFR parts 1209 and 1404.
(2) Other loose-fill insulation that cannot be mounted in the NFPA 255-96, test apparatus without a
screen or other artificial support must be tested in accordance with CAN/ULC S102.2-M88, Standard
Method of Test for Surface Burning Characteristics of Floor Coverings and Miscellaneous Materials
and Assemblies (incorporated by reference, see § 3280.4), and must have a flame spread index of 25
or less and a smoke developed index of 450 or less.
(c) Attic locations. Exposed insulation installed on the floor or ceiling forming the lower boundary of the attic
must be tested in accordance with NFPA 253-2000, Standard Method of Test for Critical Radiant Flux of
Floor Covering Systems Using a Radiant Heat Energy Source (incorporated by reference, see § 3280.4)
and must have a critical radiant flux of not less than 0.12 watt/cm2.

§ 3280.208 Requirements for foam plastic thermal insulating materials.
(a) General. Foam plastic thermal insulating materials shall not be used within the cavity of walls (not
including doors) or ceilings or be exposed to the interior of the home unless:
(1) The foam plastic insulating material is protected by an interior finish of 5⁄16-inch thick gypsum board
or equivalent material for all cavities where the material is to be installed; or
(2) The foam plastic is used as a sheathing or siding backerboard, and it:
(i)

Has a flame spread rating of 75 or less and a smoke-developed rating of 450 or less (not
including outer covering of sheathing);

(ii) Does not exceed 3⁄8-inch in thickness; and
(iii) Is separated from the interior of the manufactured home by a minimum of 2 inches of mineral
fiber insulation or an equivalent thermal barrier; or
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24 CFR 3280.208(a)(3)

(3) The foam plastic insulating material has been previously accepted by the Department for use in wall
and/or ceiling cavities of manufactured homes, and it is installed in accordance with any restrictions
imposed at the time of that acceptance; or
(4) The foam plastic insulating material has been tested as required for its location in wall and/or ceiling
cavities in accordance with testing procedures described in the Illinois Institute of Technology
Research Institute (IIT) Report, “Development of Mobile Home Fire Test Methods to Judge the FireSafe Performance of Foam Plastic Sheathing and Cavity Insulation, IITRI Fire and Safety Research
Project J-6461, 1979” or other full-scale fire tests accepted by HUD, and it is installed in a manner
consistent with the way the material was installed in the foam plastic test module. The materials
must be capable of meeting the following acceptance criteria required for their location:
(i)

Wall assemblies. The foam plastic system shall demonstrate equivalent or superior
performance to the control module as determined by:
(A) Time to reach flashover (600 °C in the upper part of the room);
(B) Time to reach an oxygen (O2) level of 14% (rate of O2 depletion), a carbon monoxide (CO)
level of 1%, a carbon dioxide (CO2) level of 6%, and a smoke level of 0.26 optical density/
meter measured at 5 feet high in the doorway; and
(C) Rate of change concentration for O2, CO, CO2 and smoke measured 3 inches below the top
of the doorway.

(ii) Ceiling assemblies. A minimum of three valid tests of the foam plastic system and one valid
test of the control module shall be evaluated to determine if the foam plastic system
demonstrates equivalent or superior performance to the control module. Individual factors to
be evaluated include intensity of cavity fire (temperature-time) and post-test damage.
(iii) Post-test damage assessment for wall and ceiling assemblies. The overall performance of each
total system shall also be evaluated in determining the acceptability of a particular foam plastic
insulating material.
(b) All foam plastic thermal insulating materials used in manufactured housing shall have a flame spread
rating of 75 or less (not including outer covering or sheathing) and a maximum smoke-developed rating of
450.
[49 FR 32008, Aug. 9, 1984, as amended at 70 FR 72043, Nov. 30, 2005. Redesignated at 78 FR 73982, Dec. 9, 2013]

§ 3280.209 Smoke alarm requirements.
(a) Labeling. Each smoke alarm required under paragraph (b) of this section must conform with the
requirements of UL 217 (incorporated by reference, see § 3280.4), or ANSI/UL 268 (incorporated by
reference, see § 3280.4), and must bear a label to evidence conformance. Combination smoke and
carbon monoxide alarms shall be listed and must bear a label to evidence conformance with UL 217 and
ANSI/UL 2034.
(b) Combination alarms. Combination smoke and carbon monoxide alarms shall be permitted to be used in
lieu of smoke alarms. If installed, such alarms must meet location requirements for both smoke alarms
and carbon monoxide alarms.
(c) Required smoke alarm locations.
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24 CFR 3280.209(c)(1)

(1) At least one smoke alarm must be installed in each of the following locations:
(i)

To protect both the living area and kitchen space. Manufacturers are encouraged to locate the
alarm in the living area remote from the kitchen and cooking appliances. A smoke alarm
located within 20 feet horizontally of a cooking appliance must incorporate a temporary
silencing feature or be of a photoelectric type.

(ii) In each room designed for sleeping.
(iii) On the ceiling of the upper level near the top or above each stairway, other than a basement
stairway, in any multistory home completed in accordance with this part or part 3282 of this
chapter. The alarm must be located so that smoke rising in the stairway cannot be prevented
from reaching the alarm by an intervening door or obstruction.
(2) For each home designed to be placed over a basement, the manufacturer must provide a smoke
alarm for the basement and must install at the factory an electrical junction box for the installation
of this smoke alarm and for its interconnection to other smoke alarms required by this section. The
instructions for installers and information for homeowners required in paragraph (f) of this section
must clearly indicate that a smoke alarm should be installed and is to be located on the basement
ceiling near the stairway.
(3) A smoke alarm required under this section must not be placed in a location that impairs its
effectiveness or in any of the following locations:
(i)

Within 3 feet horizontally from any discharge grille when a home is equipped or designed for
future installation of a roof-mounted evaporative cooler or other equipment discharging
conditioned air through a ceiling grille into the living space; and

(ii) In any location or environment that is prohibited by the terms of its listing, except as permitted
by this section.
(d) Mounting requirements.
(1) Except in rooms with peaked sloping or shed sloping ceilings with a slope of more than 1.5/12 or as
permitted pursuant to paragraph (e) of this section, smoke alarms must be mounted either:
(i)

On the ceiling at least 4 inches from each wall; or

(ii) On a wall with the top of the alarm not less than 4 inches below the ceiling, and not farther from
the ceiling than 12 inches or the distance from the ceiling specified in the smoke alarm
manufacturer's listing and instructions, whichever is less.
(2) Except as permitted pursuant to paragraph (e) of this section, in rooms with peaked sloping ceilings
with a slope of more than 1.5/12, smoke alarms must be mounted on the ceiling within 3 feet,
measured horizontally, from the peak of the ceiling; at least 4 inches, measured vertically, below the
peak of the ceiling; and at least 4 inches from any projecting structural element.
(3) Except as permitted pursuant to paragraph (e) of this section, in rooms with shed sloping ceilings
with a slope of more than 1.5/12, smoke alarms must be mounted on the ceiling within 3 feet,
measured horizontally, of the high side of the ceiling, and not closer than 4 inches from any adjoining
wall surface and from any projecting structural element.
(e) Connection to power source.
(1) Each smoke alarm must be powered from:
24 CFR 3280.209(e)(1) (enhanced display)

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(i)

24 CFR 3280.209(e)(1)(i)

The electrical system of the home as the primary power source and a battery as a secondary
power source; or

(ii) A battery rated for a 10-year life, provided the smoke alarm is listed for use with a 10-year
battery.
(2) Each smoke alarm whose primary power source is the home electrical system must be mounted on
an electrical outlet box and connected by a permanent wiring method to a general electrical circuit.
More than one smoke alarm is permitted to be placed on the same electrical circuit. The wiring
circuit for the alarm must not include any switches between the over-current protective device and
the alarm, and must not be protected by a ground fault circuit interrupter.
(3) Smoke alarms required under this section must be interconnected such that the activation of any
one smoke alarm causes the alarm to be triggered in all required smoke alarms in the home.
(f) Visible and tactile notification appliances.
(1) In addition to the smoke alarms required pursuant to this section, the manufacturer must provide
visible and listed tactile notification appliances if these appliances are ordered by the purchaser or
retailer before the home enters the first stage of production. These appliances are required to
operate from the primary power source, but are not required to operate from a secondary power
source.
(2) A visible notification appliance in a room designed for sleeping must have a minimum rating of 177
candela, except that when the visible notification appliance is wall-mounted or suspended more than
24 inches below the ceiling, a minimum rating of 110 candela is permitted.
(3) A visible notification appliance in an area other than a room designed for sleeping must have a
minimum rating of 15 candela.
(g) Testing and maintenance.
(1) Each required smoke alarm installed at the factory must be operationally tested, after conducting the
dielectric test specified in § 3280.810(a), in accordance with the alarm manufacturer's instructions.
A smoke alarm that does not function as designed during the test and is not fixed so that it functions
properly in the next retest must be replaced. Any replacement smoke alarm must be successfully
tested in accordance with this paragraph.
(2) Home manufacturers must provide specific written instructions for installers on how to inspect and
test the operation of smoke alarms during installation of the home. These instructions must indicate
that any smoke alarm that does not meet the inspection or testing requirements needs to be
replaced and retested.
(3) Home manufacturers must provide the homeowner with the alarm manufacturer's information
describing the operation, method and frequency of testing, and proper maintenance of the smoke
alarm. This information must be provided in same manner and location as the consumer manual
required by § 3282.207 of this chapter, but does not have to be incorporated into the consumer
manual. No dealer, distributor, construction contractor, or other person shall interfere with the
distribution of this information
[67 FR 12817, Mar. 19, 2002, as amended at 67 FR 49795, July 31, 2002. Redesignated at 78 FR 73982, Dec. 9, 2013; 86 FR 2518,
Jan. 12, 2021]

24 CFR 3280.209(g)(3) (enhanced display)

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24 CFR 3280.210

§ 3280.210 Fire testing.
All fire testing conducted in accordance with this subpart shall be performed by nationally recognized testing
laboratories which have expertise in fire technology. In case of dispute, the Secretary shall determine if a particular
agency is qualified to perform such fire tests.
[49 FR 32011, Aug. 9, 1984. Redesignated at 78 FR 73982, Dec. 9, 2013]

§ 3280.211 Carbon monoxide alarm requirements.
(a) Labeling. Carbon monoxide alarms shall be listed and must bear a label to evidence conformance with
ANSI/UL 2034 (incorporated by reference, see § 3280.4). Combination carbon monoxide and smoke
alarms shall be listed and must bear a label to evidence conformance with ANSI/UL 2034 and UL 217
(incorporated by reference, see § 3280.4).
(b) Required carbon monoxide alarm locations. Carbon monoxide alarms must be installed in each home
containing either a fuel burning appliance or designed by the home manufacturer to include an attached
garage. Carbon monoxide alarms must be installed outside of each separate sleeping area in the
immediate vicinity of the bedrooms and in accordance with the alarm manufacturer's installation
instructions. Where a fuel-burning appliance is located within a bedroom or its attached bathroom, a
carbon monoxide alarm must be installed within the bedroom and in accordance with the manufacturer's
installation instructions. Carbon monoxide alarms must be installed in conformance with NFPA 720
(incorporated by reference, see § 3280.4).
(c) Interconnectivity. Where more than one carbon monoxide alarm is required to be installed, the alarm
devices shall be interconnected in such a manner that the actuation of one alarm will activate all the
alarms installed.
(d) Connection to power source. Each carbon monoxide alarm must be powered from the electrical system of
the home as the primary power source and a battery as a secondary power source.
(e) Combination alarms. Combination carbon monoxide and smoke alarms shall be permitted to be used in
lieu of carbon monoxide alarms. When combination carbon monoxide and smoke alarms are used, they
shall be installed to also comply with § 3280.209.
(f) Basement applications. For each home designed to be placed over a basement, the manufacturer must
provide a carbon monoxide alarm for the basement and must install the electrical junction box for the
installation of this carbon monoxide alarm for its interconnection with other alarms required by this
section.
(g) Testing. Each required carbon monoxide alarm installed at the factory must be operationally tested, after
conducting the dielectric test specified in § 3280.810(a), in accordance with the alarm manufacturer's
instructions. A carbon monoxide alarm that does not function as designed during the test and is not
satisfactorily repaired so that it functions properly in the next retest must be replaced. Any replacement
carbon monoxide alarm must be successfully tested in accordance with this section.
[86 FR 2519, Jan. 12, 2021]

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24 CFR 3280.212

§ 3280.212 Factory constructed or site-built attached garages.
(a) When a manufactured home is designed for factory construction with an attached garage or is designed
for construction of an attached site-built garage that is not self-supported, the manufacturer must design
the manufactured home to accommodate all appropriate live and dead loads from the attached garage
structure that will be transferred through the manufactured home structure to the home's support and
anchoring systems.
(b) The design must specify the following home and garage characteristics including maximum width,
maximum sidewall height, maximum roof slope, live and dead loads, and other design limitations or
restrictions using loads provided by this Code.
(c) When a manufactured home is factory constructed with an attached garage or is constructed for the
attachment of a site-built garage, provisions must be made to provide fire separation between the garage
and the manufactured home.
(1) The garage must be separated from the manufactured home and its attic by not less than 1⁄2-inch
gypsum board or equivalent applied to the garage side of the manufactured home, separation shall
be from the underside of the floor to the underside of the roof deck and may be provided on-site as
part of an On Site Completion of Construction approval. Garages beneath habitable rooms must be
separated from all habitable rooms by 5⁄8-inch, Type X gypsum board or equivalent. Where the
separation is a floor ceiling assembly, the structure supporting the separation must also be
protected by not less than 1⁄2-inch gypsum board or equivalent. The design approval and the
manufacturer's installation instructions must also include provision for equivalent vertical or
horizontal separation between the garage and the manufactured home as appropriate.
(2) [Reserved]
(d) Openings from a garage directly into a room designated for sleeping purposes are not permitted.
(e) Other openings between the garage and the manufactured home must:
(1) Be equipped with solid wood doors not less than 13⁄8 inch in thickness, or solid or honeycomb steel
doors not less than 13⁄8 inch in thickness, or 20-minute fire-rated doors, and all doors shall be of the
self-closing type; and
(2) Be in addition to the two exterior doors required by § 3280.105.
(f) Ducts penetrating the walls or ceilings separating the manufactured home from the garage must be
constructed of a minimum No. 26 gauge steel or other approved material and must have no openings into
the garage.
(g) Installation instructions shall be provided by the home manufacturer that, in addition to addressing the fire
separation as required in this section, shall identify acceptable attachment locations, indicate design
limitations for the attachment of the garage including acceptable live and dead loads for which the home
has been designed to accommodate, and provide support and anchorage designs as necessary to
transfer all imposed loads to the ground in accordance with §§ 3285.301 and 3285.401 of this chapter.
(h) A site-built, self-supported garage is considered an add-on, per 3282.8(j)(1), that does not affect the ability
of the manufactured home to comply with the Construction and Safety Standards. The design and
construction of the garage is subject to state and or local authorities having jurisdiction.
[86 FR 2519, Jan. 12, 2021]
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24 CFR 3280.213

§ 3280.213 Factory constructed or site-built attached carports.
(a) When a manufactured home is designed for factory construction with an attached carport or is designed
for construction of an attached site-built carport, the manufacturer must design the manufactured home
to accommodate all appropriate live and dead loads from the attached carport structure that will be
transferred through the manufactured home structure to the home's support and anchoring systems.
(b) The design, including the home's installation instructions, must specify the following home and carport
characteristics including maximum width, maximum sidewall height, live and dead loads, and other
design limitations or restrictions.
(1) Alternatively, the manufacturer may provide, by design and home installation instructions, the
maximum live and dead loads, and the applied loading locations, that the home is designed to resist
from the carport, and other design limitations or restrictions.
(2) [Reserved].
(c) Homes may be designed with a factory-installed host beam (i.e., ledger board) or specific roof truss rail
for the attachment of the carport to the exterior wall of the home. The host beam (i.e., ledger board) must
be designed to transmit the appropriate live and dead loads at the interface between the carport and the
manufactured home. In cases where the carport is designed to be supported by the roof truss overhang,
the roof trusses must be designed to support the additional live and dead loads from the carport.
(1) Any portion of the host beam (i.e., ledger board) and all fasteners exposed to the weather shall be
protected in accordance with § 3280.307.
(2) [Reserved].
(d) To ensure that the attachment of the carport does not interfere with roof or attic ventilation, the
manufacturer must provide specific instructions to ensure continued compliance with the manufactured
home roof or attic ventilation requirements in accordance with § 3280.504(d).
(e) Installation instructions shall be provided by the home manufacturer that identify acceptable attachment
locations, indicate design limitations for the attachment of the carport including acceptable live and dead
loads for which the home has been designed to accommodate, and provide support and anchorage
designs as necessary to transfer all imposed loads to the ground in accordance with §§ 3285.301 and
3285.401 of this chapter.
(1) The manufacturer must ensure that any anchoring system designs incorporating anchorage to resist
combined shear wall and carport uplift loads are evaluated for adequacy to resist the combined
loads, taking into consideration the limitations of the ground anchor test and certification.
(2) [Reserved].
(f) A site-built, self-supported carport is considered an add-on, as provided by § 3282.8(j)(1), that does not
affect the ability of the manufactured home to comply with the standards. The design and construction of
the carport is subject to state and or local authorities having jurisdiction.
[86 FR 2519, Jan. 12, 2021]

Subpart D - Body and Frame Construction Requirements

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24 CFR 3280.301

§ 3280.301 Scope.
This subpart covers the minimum requirements for materials, products, equipment, and workmanship needed to
assure that the manufactured home will provide the following:
(a) Structural strength and rigidity;
(b) Protection against corrosion, decay, insects, rodents, and other similar destructive forces;
(c) Protection against wind hazards;
(d) Resistance to the elements; and
(e) Durability and economy of maintenance.
[78 FR 73982, Dec. 9, 2013]

§ 3280.302 Definitions.
The following definitions are applicable to subpart D only:
Anchor assembly means any device or other means designed to transfer home anchoring loads to the ground.
Anchoring equipment means ties, straps, cables, turnbuckles, chains, and other approved components, including
tensioning devices that are used to secure a manufactured home to anchor assemblies.
Anchoring system means a combination of anchoring equipment and anchor assemblies that will, when properly
designed and installed, resist the uplift, overturning, and lateral forces on the manufactured home and on
its support and foundation system.
Diagonal tie means a tie intended to resist horizontal or shear forces, but which may resist vertical, uplift, and
overturning forces.
Footing: means that portion of the support system that transmits loads directly to the soil.
Foundation system means a system of support that is capable of transferring all design loads to the ground,
including elements of the support system as defined in this section, or a site-built permanent foundation
that meets the requirements of 24 CFR 3282.12.
Ground anchor means a specific anchoring assembly device designed to transfer home anchoring loads to the
ground.
Loads:
(1) Dead load: means the weight of all permanent construction including walls, floors, roof, partition, and
fixed service equipment.
(2) Live load: means the weight superimposed by the use and occupancy of the manufactured home,
including wind load and snow load, but not including dead load.
(3) Wind load: means the lateral or vertical pressure or uplift on the manufactured home due to wind
blowing in any direction.
Main frame: means the structural component on which is mounted the body of the manufactured home.

24 CFR 3280.302 “Main frame:” (enhanced display)

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24 CFR 3280.302 “Pier:”

Pier: means that portion of the support system between the footing and manufactured home exclusive of caps
and shims.
Sheathing: means material which is applied on the exterior side of a building frame under the exterior weather
resistant covering.
Stabilizing devices means all components of the anchoring and support systems, such as piers, footings, ties,
anchoring equipment, anchoring assemblies, or any other equipment, materials, and methods of
construction that support and secure the manufactured home to the ground.
Support system: means a combination of footings, piers, caps, and shims that will, when properly installed,
support the manufactured home.
Support system means any pilings, columns, footings, piers, foundation walls, shims, and any combination
thereof that, when properly installed, support the manufactured home.
Tie:

means straps, cable, or securing devices used to connect the manufactured home to ground anchors.

Vertical tie: means a tie intended to resist the uplifting or overturning forces.
[58 FR 55005, Oct. 25, 1993; 59 FR 15113, Mar. 31, 1994, as amended at 72 FR 59361, Oct. 19, 2007]

§ 3280.303 General requirements.
(a) Minimum requirements. The design and construction of a manufactured home shall conform with the
provisions of this standard. Requirements for any size, weight, or quality of material modified by the terms
of minimum, not less than, at least, and similar expressions are minimum standards. The manufacturer or
installer may exceed these standards provided such deviation does not result in any inferior installation or
defeat the purpose and intent of this standard.
(b) Construction. All construction methods shall be in conformance with accepted engineering practices to
insure durable, livable, and safe housing and shall demonstrate acceptable workmanship reflecting
journeyman quality of work of the various trades.
(c) Structural analysis. The strength and rigidity of the component parts and/or the integrated structure shall
be determined by engineering analysis or by suitable load tests to simulate the actual loads and
conditions of application that occur. (See subparts E and J.)
(d) [Reserved]
(e) New materials and methods.
(1) Any new material or method of construction not provided for in this standard and any material or
method of questioned suitability proposed for use in the manufacture of the structure shall
nevertheless conform in performance to the requirements of this standard.
(2) Unless based on accepted engineering design for the use indicated, all new manufactured home
materials, equipment, systems or methods of construction not provided for in this standard shall be
subjected to the tests specified in paragraph (g) of this section.
(f) Allowable design stress. The design stresses of all materials shall conform to accepted engineering
practice. The use of materials not certified as to strength or stress grade shall be limited to the minimum
allowable stresses under accepted engineering practice.

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24 CFR 3280.303(g)

(g) Alternative test procedures. In the absence of recognized testing procedures either in the Standards in this
part or in the applicable provisions of those standards incorporated in this part by reference, the
manufacturer electing this option must develop or cause to be developed testing procedures to
demonstrate the structural properties and significant characteristics of the material, assembly,
subassembly component, or member, except for testing methods involving one-piece metal roofing as
would be required in § 3280.305(c)(1)(iii). Such testing procedures become part of the manufacturer's
approved design. Such tests must be witnessed by an independent licensed professional engineer or
architect or by a recognized testing organization. Copies of the test results must be kept on file by the
manufactured home manufacturer.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55005, Oct. 25, 1993; 59 FR 2469,
Jan. 14, 1994; 70 FR 72043, Nov. 30, 2005]

§ 3280.304 Materials.
(a) Dimension and board lumber shall not exceed 19 percent moisture content at time of installation.
(b)
(1) Standards for some of the generally used materials and methods of construction are listed in the
following table:

ALUMINUM
Aluminum Design Manual, Specifications and Guidelines for Aluminum Structures, Part 1-A, Sixth Edition,
October 1994, and Part 1-B, First Edition, October 1994.

STEEL
Specification for Structural Steel Buildings - Allowable Stress Design and Plastic Design - AISC-S335,
1989. The following parts of this reference standard are not applicable: 1.3.3, 1.3.4, 1.3.5, 1.3.6, 1.4.6,
1.5.1.5, 1.5.5, 1.6, 1.7, 1.8, 1.9, 1.10.4 through 1.10.7, 1.10.9, 1.11, 1.13, 1.14.5, 1.17.7 through 1.17.9,
1.19.1, 1.19.3, 1.20, 1.21, 1.23.7, 1.24, 1.25.1 through 1.25.5, 1.26.4, 2.3, 2.4, 2.8 through 2.10.
Specification for the Design of Cold-Formed Steel Structural Members - AISI-1996.
Specification for the Design of Cold-Formed Stainless Steel Structural Members - SEI/ASCE 8-02, 2002.
Standard Specifications Load Tables and Weight Tables for Steel Joists and Joist Girders, SJI, Fortieth
Edition, 1994.
Structural Applications of Steel Cables for Buildings - ASCE19, 1996.
Standard Specification for Strapping, Flat Steel and Seals - ASTM D3953, 1991.

WOOD AND WOOD PRODUCTS
Basic Hardboard - ANSI/AHA A135.4-1995.
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24 CFR 3280.304(b)(1)

Prefinished Hardboard Paneling - ANSI/AHA A135.5-1995.
Hardboard Siding - ANSI/AHA A135.6-1998.
American National Standard for Hardwood and Decorative Plywood - ANSI/HPVA HP-1-1994 (Approved
1995).
Structural Design Guide for Hardwood Plywood Wall Panels - HPVA Design Guide HP-SG-96, 1996.
For wood products - Structural Glued Laminated Timber - ANSI/AITC A190.1-1992.
Construction and Industrial Plywood (With Typical APA Trademarks) - PS 1-95.
APA Design/Construction Guide, Residential and Commercial - APA E30-P-1996.
Design Specifications for Metal Plate and Wood Connected Trusses - TPI-85.
Design and Fabrication of All-Plywood Beams - APA H-815E (PDS Supplement #5), 1995.
Panel Design Specification - APA D410A, 2004.
Design and Fabrication of Glued Plywood-Lumber Beams, Supplement# 2 - APA S 812R, 1992
(incorporated by reference, see § 3280.4).
Design and Fabrication of Plywood Curved Panels - APA-S 811M, Suppl. 1, 1990.
Design and Fabrication of Plywood Sandwich Panels, Supplement #4 - APA U 814H, 1990 (incorporated by
reference, see § 3280.4).
Performance Standard for Wood-Based Structural Use Panels - NIST PS 2-04, 2004 (incorporated by
reference, see § 3280.4).
Design and Fabrication of Plywood Stressed-Skin Panels, Supplement 3 - APA-U 813L, 1992 (incorporated
by reference, see § 3280.4).
National Design Specifications for Wood Construction, 2001 Edition, with Supplement, Design Values for
Wood Construction, NDS-2001, ANSI/AFPA.
Wood Structural Design Data, 1986 Edition with 1992 Revisions, AFPA.
Span Tables for Joists and Rafters - PS-20-70, 1993, AFPA.
Design Values for Joists and Rafters 1992, AFPA.
Particleboard - ANSI A208.1-1999.

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24 CFR 3280.304(b)(2)

Voluntary Specifications for Aluminum, Vinyl (PVC) and Wood Windows and Glass Doors - ANSI/AAMA/
NWWDA 101/I.S.2-97.
Standard Test Methods for Puncture and Stiffness of Paperboard, and Corrugated and Solid Fiberboard ASTM D781, 1973.
Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base Materials ASTM D 4442-92 (Re-approved 1997), 1997.
Standard Test Methods for Use and Calibration of Hand-Held Moisture Meters - ASTM D4444, 1992.
Engineered Wood Construction Guide - APA E30R 2001 (incorporated by reference, see § 3280.4).
Medium Density Fiberboard (MDF) For Interior Applications - ANSI A208.2-2002 (incorporated by
reference, see § 3280.4).

OTHER
Standard Specification for Gypsum Wallboard - ASTM C 36/C 36M-99, 1999.

FASTENERS
National Evaluation Report, Power Driven Staples, Nails, and Allied Fasteners for Use in All Types of
Building Construction - NER-272, 1997.

UNCLASSIFIED
Minimum Design Loads for Buildings and Other Structures - ASCE 7-1988.
Standard for Safety Glazing Materials used in Buildings - Safety Performance Specifications and Methods
of Test, ANSI Z97.1-2004 (incorporated by reference, see § 3280.4).
(2) Materials and methods of construction utilized in the design and construction of manufactured
homes which are covered by the standards in the following table, or any applicable portion thereof
shall comply with these requirements.
(3) Engineering analysis and testing methods contained in these references shall be utilized to judge
conformance with accepted engineering practices required in § 3280.303(c).
(4) Materials and methods of installation conforming to these standards shall be considered acceptable
when installed in conformance with the requirements of this part.
(5) Materials meeting the standards (or the applicable portion thereof) are considered acceptable unless
otherwise specified herein or unless substantial doubt exists as to conformance.
(c) Wood products shall be identified as complying with the appropriate standards.
[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 961, Jan. 4, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at
58 FR 55006, Oct. 25, 1993; 59 FR 15113, Mar. 31, 1994; 70 FR 72043, Nov. 30, 2005; 78 FR 73982, Dec. 9, 2013]
24 CFR 3280.304(c) (enhanced display)

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24 CFR 3280.305

§ 3280.305 Structural design requirements.
(a) General. Each manufactured home must be designed and constructed as a completely integrated
structure capable of sustaining the design load requirements of this part and must be capable of
transmitting these loads to stabilizing devices without exceeding the allowable stresses or deflections.
Roof framing must be securely fastened to wall framing, walls to floor structure, and floor structure to
chassis to secure and maintain continuity between the floor and chassis, so as to resist wind overturning,
uplift, and sliding as imposed by design loads in this part. In multistory construction, each story must be
securely fastened to the story above and/or below to provide continuity and resist design loads in this
part. Uncompressed finished flooring greater than 1⁄8 inch in thickness must not extend beneath loadbearing walls that are fastened to the floor structure.
(b) Design loads (1) Design dead loads. Design dead loads shall be the actual dead load supported by the structural
assembly under consideration.
(2) Design live loads. The design live loads and wind and snow loads shall be as specified in this section
and shall be considered to be uniformly distributed. The roof live load or snow load shall not be
considered as acting simultaneously with the wind load and the roof live or snow load and floor live
loads shall not be considered as resisting the overturning moment due to wind.
(3) When engineering calculations are performed, allowable unit stresses may be increased as provided
in the documents referenced in § 3280.304 except as otherwise indicated in §§ 3280.304(b)(1) and
3280.306(a).
(4) Whenever the roof slope does not exceed 20 degrees, the design horizontal wind loads required by §
3280.305(c)(1) may be determined without including the vertical roof projection of the manufactured
home. However, regardless of the roof slope of the manufactured home, the vertical roof projection
shall be included when determining the wind loading for split level or clerestory-type roof systems.
(c) Wind, snow, and roof loads (1) Wind loads - design requirements.
(i)

Standard wind loads (Zone I ). When a manufactured home is not designed to resist the wind
loads for high-wind areas (Zone II or Zone III) specified in paragraph (c)(1)(ii) of this section, the
manufactured home and each of its wind-resisting parts and portions must be designed for
horizontal wind loads of not less than 15 psf and a net uplift roof load of not less than 9 psf.
The net uplift roof load must not be reduced by the dead load of the roof structure for the
purposes of engineering design or structural load testing.

(ii) Wind loads for high wind areas (Zone II and Zone III). When designed for high wind areas (Zone
II and Zone III), the manufactured home, each of its wind resisting parts (including, but not
limited to, shear walls, diaphragms, ridge beams, and their fastening and anchoring systems),
and its components and cladding materials (including, but not limited to, roof trusses, wall
studs, exterior sheathing, roofing and siding materials, exterior glazing, and their connections
and fasteners) shall be designed by a Professional Engineer or Architect to resist:
(A) The design wind loads for Exposure C specified in ANSI/ASCE 7-88, “Minimum Design
Loads for Buildings and Other Structures,” for a fifty-year recurrence interval, and a design
wind speed of 100 mph, as specified for Wind Zone II, or 110 mph, as specified for Wind
Zone III (Basic Wind Zone Map); or
24 CFR 3280.305(c)(1)(ii)(A) (enhanced display)

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24 CFR 3280.305(c)(1)(ii)(B)

(B) The wind pressures specified in the following table:

Table of Design Wind Pressures
Element

Wind zone II
design wind
speed 100 MPH

Wind zone III
design wind
speed 110 MPH

Anchorage for lateral and vertical stability (See §
3280.306(a)):
Net Horizontal Drag1 2:

3

±39 PSF

5

−27 PSF

−32 PSF

Shearwalls, Diaphragms and their Fastening and
Anchorage Systems1 2

±39 PSF

±47 PSF

Ridge beams and other Main Roof Support Beams
(Beams supporting expanding room sections, etc.)

−30 PSF

−36 PSF

4

Uplift :

3

±47 PSF

Main wind force resisting system:

Components and cladding:
Roof trusses4 in all areas; trusses shall be doubled
within 3′-0′ from each end of the roof

5

−39 PSF

5

−47 PSF

Exterior roof coverings, sheathing and fastenings4,6,7 in
all areas except the following

5

−39 PSF

5

−47 PSF

Within 3′-0′ from each gable end (overhang at end
wall) of the roof or endwall if no overhang is
provided4,6,7

5

−73 PSF

5

−89 PSF

Within 3′-0′ from the ridge and eave (overhang at
sidewall) or sidewall if no eave is provided4,6,7

5

−51 PSF

5

−62 PSF

Eaves (Overhangs at Sidewalls)4,6,7

5

−51 PSF

5

−62 PSF

Endwalls)4,6,7

5

−73 PSF

5

−89 PSF

Gables (Overhangs at

Wall studs in sidewalls and endwalls, exterior windows and
sliding glass doors (glazing and framing), exterior
coverings, sheathing and fastenings8:
Within 3′-0′ from each corner of the sidewall and
endwall

±48 PSF

±58 PSF

All other areas

±38 PSF

±46 PSF

NOTES:
1

The net horizontal drag of ±39 PSF to be used in calculating Anchorage for Lateral and
Vertical Stability and for the design of Main Wind Force Resisting Systems is based on a
distribution of wind pressures of + 0.8 or + 24 PSF to the windward wall and −0.5 or −15
PSF to the leeward wall.
2

Horizontal drag pressures need not be applied to roof projections when the roof slope
does not exceed 20 degrees.

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24 CFR 3280.305(c)(1)(iii)

3

+ sign would mean pressures are acting towards or on the structure; − sign means
pressures are acting away from the structure; ±sign means forces can act in either
direction, towards or away from the structure.
4

Design values in this “Table” are only applicable to roof slopes between 10 degrees
(nominal 2/12 slope) and 30 degrees.
5

The design uplift pressures are the same whether they are applied normal to the surface
of the roof or to the horizontal projection of the roof.
6

Shingle roof coverings that are secured with 6 fasteners per shingle through an
underlayment which is cemented to a 3/8” structural rated roof sheathing need not be
evaluated for these design wind pressures.
7

Structural rated roof sheathing that is at least 3/8” in thickness, installed with the long
dimension perpendicular to roof framing supports, and secured with fasteners at 4” on
center within 3′-0′ of each gable end or endwall if no overhang is provided and 6” on center
in all other areas, need not be evaluated for these design wind pressures.
8

Exterior coverings that are secured at 6″ o.c. to a 3/8″ structural rated sheathing that is
fastened to wall framing members at 6″ on center need not be evaluated for these design
wind pressures.
(iii) One-piece metal roofing capable of resisting the design wind pressures for “Components and
Cladding: (Exterior roof coverings)” in the Table for Design Wind Pressures in this section is
allowed to be used without structural sheathing, provided the metal roofing is tested using
procedures that have been approved by HUD and that meet all requirements of §§ 3280.303(c)
and (g) and 3280.401.
(2) Wind loads - zone designations. The Wind Zone and specific wind design load requirements are
determined by the fastest basic wind speed (mph) within each Zone and the intended location,
based on the Basic Wind Zone Map, as follows:
(i)

Wind Zone I. Wind Zone I consists of those areas on the Basic Wind Zone Map that are not
identified in paragraphs (c)(2)(ii) or (iii) of this section as being within Wind Zone II or III,
respectively.

(ii) Wind Zone II. ....100 mph. The following areas are deemed to be within Wind Zone II of the Basic
Wind Zone Map:
Local governments: The following local governments listed by State (counties, unless specified
otherwise):
Alabama: Baldwin and Mobile.
Florida: All counties except those identified in paragraph (c)(1)(i)(C) of this section as within Wind
Zone III.
Georgia: Bryan, Camden, Chatham, Glynn, Liberty, McIntosh.
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24 CFR 3280.305(c)(2)(iii)

Louisiana: Parishes of Acadia, Allen, Ascension, Assumption, Calcasieu, Cameron, East Baton Rouge,
East Feliciana, Evangeline, Iberia, Iberville, Jefferson Davis, LaFayette, Livingston, Pointe Coupee, St.
Helena, St. James, St. John the Baptist, St. Landry, St. Martin, St. Tammany, Tangipahoa, Vermillion,
Washington, West Baton Rouge, and West Feliciana.
Maine: Hancock and Washington.
Massachusetts: Barnstable, Bristol, Dukes, Nantucket, and Plymouth.
Mississippi: George, Hancock, Harrison, Jackson, Pearl River, and Stone.
North Carolina: Beaufort, Brunswick, Camden, Chowan, Columbus, Craven, Currituck, Jones, New
Hanover, Onslow, Pamlico, Pasquotank, Pender, Perquimans, Tyrrell, and Washington.
South Carolina: Beaufort, Berkeley, Charleston, Colleton, Dorchester, Georgetown, Horry, Jasper, and
Williamsburg.
Texas: Aransas, Brazoria, Calhoun, Cameron, Chambers, Galveston, Jefferson, Kenedy, Kleberg,
Matagorda, Nueces, Orange, Refugio, San Patricio, and Willacy.
Virginia: Cities of Chesapeake, Norfolk, Portsmouth, Princess Anne, and Virginia Beach.
(iii) Wind Zone III. ....110 mph. The following areas are considered to be within Wind Zone III of the
Basic Wind Zone Map:
(A) States and Territories: The entire State of Hawaii, the coastal regions of Alaska (as
determined by the 90 mph isotach on the ANSI/ASCE 7-88 map), and all of the U.S.
Territories of American Samoa, Guam, Northern Mariana Islands, Puerto Rico, Trust
Territory of the Pacific Islands, and the United States Virgin Islands.
(B) Local governments: The following local governments listed by State (counties, unless
specified otherwise):
Florida: Broward, Charlotte, Collier, Dade, Franklin, Gulf, Hendry, Lee, Martin, Manatee, Monroe,
Palm Beach, Pinellas, and Sarasota.
Louisiana: Parishes of Jefferson, La Fourche, Orleans, Plaquemines, St. Bernard, St. Charles, St.
Mary, and Terrabonne.
North Carolina: Carteret, Dare, and Hyde.
(iv) Consideration of local requirements. For areas where wind mapping data or records or the
requirements of the State or local authority indicate wind speeds in excess of those identified in
this section, the Department may establish, through rulemaking, more stringent requirements
for manufactured homes to be installed in such areas.
(3) Snow and roof loads.

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(i)

24 CFR 3280.305(c)(3)(i)

Flat, curved and pitched roofs shall be designed to resist the following live loads, applied
downward on the horizontal projection as appropriate for the design zone marked on the
manufactured home:
Zone (see Map in § 3280.305(c)(4))

Pounds per square foot

North Zone

40

Middle Zone

30

South Zone

20

(A) North Roof Load Zone. The following counties in each of the following states are deemed
to be within the North Roof Load Zone:
Maine - Aroostook, Piscataquis, Somerset, Penobscot, Waldo, Knox, Hancock, and Washington.
Alaska - All Counties
(B) Middle Roof Load Zone. The following counties in each of the following states are deemed
to be within the Middle Roof Load Zone:
States
South Dakota

Minnesota

24 CFR 3280.305(c)(3)(i)(B) (enhanced display)

Counties
Grant

Brookings

Hanson

Lincoln

Codington

Miner

Minnehaha

Yankton

Deuel

Lake

Hutchinson

Union

Hamlin

Moody

Turner

Clay

Kingsbury

McCook

Koochiching

Stearns

Renville

Sibley

Itasca

Swift

McLeod

Nicollet

Hubbard

Kandiyohi

Carver

Blue Earth

Cass

Meeker

Dakota

Martin

Crow Wing

Wright

Goodhue

Watonwan

Aitkin

Lac qui Parle

Wabasha

Brown

St. Louis

Chippewa

Winona

Redwood

Lake

Yellow Medicine

Fillmore

Lyon

Cook

Mille Lacs

Mower

Lincoln

Carlton

Kanabec

Olmsted

Pipestone

Pine

Benton

Dodge

Murray

Wadena

Isanti

Rice

Cottonwood

Todd

Sherburne

Steele

Jackson

Morrison

Anoka

Freeborn

Nobles

Douglas

Chisapo

Faribault

Rock

Grant

Washington

Waseca

Stevens

Hennepin

Le Sueur

Pope

Ramsey

Scott
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States
Iowa

Wisconsin

24 CFR 3280.305(c)(3)(i)(B)

Counties
Hancock

Mitchell

Hamilton

Buena Vista

Lyon

Howard

Webster

Cherokee

Osceola

Chickasaw

Calhoun

Plymouth

Dickinson

Butler

Sac

Sioux

Emmet

Floyd

Ida

O'Brien

Kossuth

Cerro Gordo

Humboldt

Clay

Winnebago

Franklin

Pocahontas

Wright

Worth

Hardin

Palo Alto

Douglas

Oconto

Pepin

Lincoln

Bayfield

Menominee

Pierce

Oneida

Ashland

Langlade

Dunn

Polk

Iron

Marathon

Eau Claire

Burnett

Vilas

Clark

Chippewa

Washburn

Forest

Jackson

Rusk

Sawyer

Florence

Trempealeau

Barron

Price

Marinette

Buffalo

Taylor

Door

Houghton

Iron

Presque Isle

Wexford

Baraga

Dickinson

Charlevoix

Benzie

Marquette

Menominee

Montmorency

Grand Traverse

Alger

Delta

Alpena

Kalkaska

Luce

Schoolcraft

Alcona

Oscoda

Chippewa

Mackinac

Ogemaw

Otsego

Keweenaw

Cheyboygan

Roscommon

Leelanau

Ontonagon

Emmet

Missaukee

Antrim

Gogebic

Crawford

St. Lawrence

Herkimer

Onondaga

Genesee

Franklin

Lewis

Madison

Orleans

Clinton

Oswego

Cayuga

Niagara

Essex

Jefferson

Seneca

Erie

Hamilton

Oneida

Wayne

Wyoming

Warren

Fulton

Ontario

Monroe

Saratoga

Montgomery

Yates

Washington

Schenectady

Livingston

St. Croix
Michigan

New York

Massachusetts

Essex

Maine

Franklin

Kennebec

Lincoln

Cumberland

Oxford

Androscoggin

Sagadahoc

York

Montana

All Counties

Idaho

All Counties

Colorado

All Counties

24 CFR 3280.305(c)(3)(i)(B) (enhanced display)

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States

24 CFR 3280.305(c)(3)(i)(C)

Counties

Wyoming

All Counties

Utah

All Counties

Vermont

Franklin

Orleans

Caledonia

Addison

Grand Isle

Essex

Washington

Rutland

Lamoille

Chittenden

Orange

Windsor

New Hampshire

All Counties

(C) South Roof Load Zone. The states and counties that are not listed for the North Roof Load
Zone in paragraph (c)(3)(i)(A) of this section, or the Middle Roof Load Zone in paragraph
(c)(3)(i)(B) of this section, are deemed to be within the South Roof Load Zone.
(ii) Consideration of local requirements. For exposures in areas (mountainous or other) where
recognized snow records, wind records, or the requirements of the State or local authority
indicate significant differences from the loads stated in this paragraph (c)(3), the Department
may establish, through rulemaking, more stringent requirements for manufactured homes to be
installed in such areas. For snow loads, such requirements must be based on a roof snow load
of 0.6 of the ground snow load for areas exposed to wind and a roof snow load of 0.8 of the
ground snow load for sheltered areas.
(iii) Eaves and cornices shall be designed for a net uplift pressure of 2.5 times the design uplift
wind pressure cited in § 3280.305(c)(1)(i) for Wind Zone I, and for the design pressures cited in
§ 3280.305(c)(1)(ii) for Wind Zones II and III.
(iv) Skylights must be capable of withstanding roof loads as specified in paragraphs (c)(3)(i) or
(c)(3)(ii) of this section. Skylights must be listed and tested in accordance with AAMA 1600/
I.S.7-00, 2003, Voluntary Specification for Skylights.
(4) Data plate requirements. The Data Plate posted in the manufactured home (see § 3280.5) shall
designate the wind and roof load zones or, if designed for higher loads, the actual design external
snow and wind loads for which the home has been designed. The Data Plate shall include
reproductions of the Load Zone Maps shown in this paragraph (c)(4), with any related information.
The Load Zone Maps shall be not less than either 31⁄2 in. by 21⁄4 in., or one-half the size illustrated in
the Code of Federal Regulations.

24 CFR 3280.305(c)(4) (enhanced display)

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24 CFR 3280.305(c)(4) (enhanced display)

24 CFR 3280.305(c)(4)

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24 CFR 3280.305(c)(4) (enhanced display)

24 CFR 3280.305(c)(4)

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24 CFR 3280.305(d)

(d) Design load deflection.
(1) When a structural assembly is subjected to total design live loads, the deflection for structural
framing members shall not exceed the following (where L equals the clear span between supports or
two times the length of a cantilever):
Floor - L/240
Roof and ceiling - L/180
Headers, beams, and girders (vertical load) - L/180
Walls and partitions - L/180
(2) The allowable eave or cornice deflection for uplift is to be measured at the design uplift load of 9 psf
for Wind Zone I, and at the design uplift pressure cited in paragraph (c)(1)(ii) of this section for Wind
Zones II and III. The allowable deflection shall be (2 × Lc)/180, where Lc is the measured horizontal
eave projection from the wall.
(e) Fastening of structural systems.
(1) Roof framing must be securely fastened to wall framing, walls to floor structure, and floor structure
to chassis, to secure and maintain continuity between the floor and chassis in order to resist wind
overturning, uplift, and sliding, and to provide continuous load paths for these forces to the
foundation or anchorage system. The number and type of fasteners used must be capable of
transferring all forces between elements being joined. In multistory construction, each story must be
securely fastened to the story above and/or below to provide continuity and resist design loads in
this section.
(2) For Wind Zone II and Wind Zone III, roof framing members must be securely fastened at the vertical
bearing points to resist design overturning, uplift, and sliding forces. When engineered connectors
are not installed, roof framing members must be secured at the vertical bearing points to wall
framing members (studs), and wall framing members (studs) must be secured to floor framing
members, with 0.016 inch base metal, minimum steel strapping or engineered connectors, or by a
combination of 0.016 inch base metal, minimum steel strapping or engineered connectors, and
structural-rated wall sheathing that overlaps the roof and floor system if substantiated by structural
analysis or by suitable load tests. Steel strapping or engineered connectors are to be installed at a
maximum spacing of 24 inches on center in Wind Zone II, and 16 inches on center in Wind Zone III.
Exception: Where substantiated by structural analysis or suitable load tests, the 0.016 inch base
metal minimum steel strapping or engineered connectors may be omitted at the roof to wall and/or
wall to floor connections, when structural rated sheathing that overlaps the roof and wall and/or wall
and floor is capable of resisting the applicable design wind loads.
(f) Walls. The walls shall be of sufficient strength to withstand the load requirements as defined in §
3280.305(c) of this part, without exceeding the deflections as specified in § 3280.305(d). The
connections between the bearing walls, floor, and roof framework members shall be fabricated in such a
manner as to provide support for the material used to enclose the manufactured home and to provide for
transfer of all lateral and vertical loads to the floor and chassis.
(1) Except where substantiated by engineering analysis or tests, studs shall not be notched or drilled in
the middle one-third of their length.
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24 CFR 3280.305(f)(2)

(2) Interior walls and partitions shall be constructed with structural capacity adequate for the intended
purpose and shall be capable of resisting a horizontal load of not less than five pounds per square
foot. An allowable stress increase of 1.33 times the permitted published design values may be used
in the design of wood framed interior partitions. Finish of walls and partitions shall be securely
fastened to wall framing.
(g) Floors.
(1) Floor assemblies shall be designed in accordance with accepted engineering practice standards to
support a minimum uniform live load of 40 lb/ft2 plus the dead load of the materials. In addition (but
not simultaneously), floors shall be able to support a 200-pound concentrated load on a one-inch
diameter disc at the most critical location with a maximum deflection not to exceed one-eighth inch
relative to floor framing. Perimeter wood joists of more than six inches depth shall be stabilized
against overturning from superimposed loads as follows: at ends by solid blocking not less than
two-inch thickness by full depth of joist, or by connecting to a continuous header not less than twoinch thickness and not less than the depth of the joist with connecting devices; at eight-feet
maximum intermediate spacing by solid blocking or by wood cross-bridging of not less than one
inch by three inches, metal cross-bridging of equal strength, or by other approved methods.
(2) Wood, wood fiber or plywood floors or subfloors in kitchens, bathrooms (including toilet
compartments), laundry areas, water heater compartments, and any other areas subject to
excessive moisture shall be moisture resistant or shall be made moisture resistant by sealing or by
an overlay of nonabsorbent material applied with water-resistant adhesive. Use of one of the
following methods would meet this requirement:
(i)

Sealing the floor with a water-resistant sealer; or

(ii) Installing an overlay of a non-absorbent floor covering material applied with water-resistant
adhesive; or
(iii) Direct application of a water-resistant sealer to the exposed wood floor area when covered with
a non-absorbent overlay; or
(iv) The use of a non-absorbent floor covering which may be installed without a continuous
application of a water-resistant adhesive or sealant when the floor covering meets the following
criteria:
(A) The covering is a continuous membrane with any seams or patches seam bonded or
welded to preserve the continuity of the floor covering; and
(B) The floor is protected at all penetrations in these areas by sealing with a compatible waterresistant adhesive or sealant to prevent moisture from migrating under the nonabsorbent
floor covering; and
(C) The covering is fastened around the perimeter of the subfloor in accordance with the floor
covering manufacturer's instructions; and,
(D) The covering is designed to be installed to prevent moisture penetration without the use of
a water-resistant adhesive or sealer except as required in this paragraph (g). The vertical
edges of penetrations for plumbing shall be covered with a moisture-resistant adhesive or
sealant. The vertical penetrations located under the bottom plates of perimeter walls of
rooms, areas, or compartments are not required to be sealed; this does not include walls
or partitions within the rooms or areas.
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24 CFR 3280.305(g)(3)

(3) Wood panel products used as floor or subfloor materials on the exterior of the home, such as in
recessed entryways, must be rated for exterior exposure and protected from moisture by sealing or
applying nonabsorbent overlay with water resistant adhesive.
(4) Carpet or carpet pads shall not be installed under concealed spaces subject to excessive moisture,
such as plumbing fixture spaces, floor areas under installed laundry equipment. Carpet may be
installed in laundry space provided:
(i)

The appliances are not provided;

(ii) The conditions of paragraph (g)(2) of this section are followed; and
(iii) Instructions are provided to remove carpet when appliances are installed.
(5) Except where substantiated by engineering analysis or tests:
(i)

Notches on the ends of joists shall not exceed one-fourth the joist depth.

(ii) Holes bored in joists shall not be within 2 inches of the top or bottom of the joist, and the
diameter of any such hole shall not exceed one-third the depth of the joist.
(iii) Notches in the top or bottom of the joists shall not exceed one-sixth the depth and shall not be
located in the middle third of the span.
(6) Bottom board material (with or without patches) must meet or exceed the level of 48 inch-pounds of
puncture resistance as tested by the Beach Puncture Test in accordance with Standard Test
Methods for Puncture and Stiffness of Paperboard, and Corrugated and Solid Fiberboard, ASTM
D781-1968 (Reapproved 1973) (incorporated by reference, see § 3280.4). The material must be
suitable for patches and the patch life must be equivalent to the material life. Patch installation
instruction must be included in the manufactured home manufacturer's instructions. The bottom
board material must be tight fitted against all penetrations.
(h) Roofs.
(1) Roofs shall be of sufficient strength to withstand the load requirements as defined in § 3280.305 (b)
and (c) without exceeding the deflections specified in § 3280.305(d). The connections between roof
framework members and bearing walls shall be fabricated in such a manner to provide for the
transfer of design vertical and horizontal loads to the bearing walls and to resist uplift forces.
(2) Roofing membranes shall be of sufficient rigidity to prevent deflection which would permit ponding of
water or separation of seams due to wind, snow, ice, erection or transportation forces.
(3) Cutting of roof framework members for passage of electrical, plumbing or mechanical systems shall
not be allowed except where substantiated by engineering analysis.
(4) All roof penetrations for electrical, plumbing or mechanical systems shall be properly flashed and
sealed. In addition, where a metal roof membrane is penetrated, a wood backer shall be installed.
The backer plate shall be not less than 5⁄16 inch plywood, with exterior glues, secured to the roof
framing system beneath the metal roof, and shall be of a size to assure that all screws securing the
flashing are held by the backer plate.
(5) Portions of roof assemblies, including, but not limited to, dormers, gables, crickets, hinged roof
sections, sheathing, roof coverings, underlayments, flashings, and eaves and overhangs are
permitted to be assembled and installed on site in accordance with 24 CFR part 3282, subpart M,
provided that the requirements in paragraphs (h)(5)(i) through (iv) of this section are met.
24 CFR 3280.305(h)(5) (enhanced display)

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(i)

24 CFR 3280.305(h)(5)(i)

Approved installation instructions must be provided that include requirements for the following
items:
(A) Materials, installation, and structural connections complying with this section;
(B) Installation and fastening of sheathing and roof coverings;
(C) Installation of appliance vent systems in accordance with § 3280.710;
(D) Installation of plumbing vents as required by § 3280.611; and
(E) Installation of attic ventilation in accordance with § 3280.504(c).

(ii) The installation instructions specified in paragraph (h)(5)(i) of this section must include
drawings, details, and instructions as necessary to assure that the on-site work complies with
the approved design.
(iii) The installation instructions specified in paragraph (h)(5)(i) of this section must provide for
inspection of the work at the installation site. As necessary to ensure conformance, inspection
panels may be required, or inspections may need to occur in stages that assure inspections are
performed before any work is concealed. Such inspection procedures shall be addressed in the
approved installation instructions.
(iv) Temporary weather protection must be provided per § 3280.307(e).
(i)

Frame construction. The frame shall be capable of transmitting all design loads to stabilizing devices
without exceeding the allowable load and deflections of this section. The frame shall also be capable of
withstanding the effects of transportation shock and vibration without degradation as required by subpart
J.
(1) [Reserved]
(2) Protection of metal frames against corrosion. Metal frames shall be made corrosion resistant or
protected against corrosion. Metal frames may be protected against corrosion by painting.

(j)

Welded connections.
(1) All welds must be made in accordance with the applicable provisions of the Specification for
Structural Steel Buildings, Allowable Stress Design and Plastic Design, AISC-S335, 1989; the
Specification for the Design of Cold-Formed Steel Structural Members, AISI, 1996; and the
Specification for the Design of Cold-Formed Stainless Steel Structural Members, SEI/ASCE 8-02,
2002.
(2) Regardless of the provisions of any reference standard contained in this subpart, deposits of weld
slag or flux shall be required to be removed only from welded joints at the following locations:
(i)

Drawbar and coupling mechanisms;

(ii) Main member splices, and
(iii) Spring hanger to main member connections.
(k) Attics.

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24 CFR 3280.305(k)(1)

(1) For roofs with slopes 7:12 or greater, the area of the attic floor that meets the ceiling-height/livingspace requirements of these construction and safety standards must be designed to resist a
minimum design live load of 40 pounds per square foot (psf) in accordance with paragraph (g) of
this section.
(2) For roofs with slopes less than 7:12 that contain an attic area or for portions of roofs with slopes
7:12 or greater that do meet the ceiling height/living space requirements of the standards, the attic
floor must be designed for a storage live load of 20 pounds per square foot (psf).
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 44 FR 66195, Nov. 19, 1979; 52 FR 4582,
Feb. 12, 1987; 58 FR 55006, Oct. 25, 1993; 59 FR 2469, Jan. 14, 1994; 59 FR 15113, 15114, Mar. 31, 1994; 62 FR 54547, Oct. 20,
1997; 70 FR 72043, Nov. 30, 2005; 71 FR 19638, Apr. 17, 2006; 78 FR 73983, Dec. 9, 2013; 80 FR 53727, Sept. 8, 2015; 86 FR 2520,
Jan. 12, 2021; 86 FR 10457, Feb. 22, 2021]

§ 3280.306 Windstorm protection.
(a) Provisions for support and anchoring systems. Each manufactured home shall have provisions for
support/anchoring or foundation systems that, when properly designed and installed, will resist
overturning and lateral movement (sliding) of the manufactured home as imposed by the respective
design loads. For Wind Zone I, the design wind loads to be used for calculating resistance to overturning
and lateral movement shall be the simultaneous application of the wind loads indicated in §
3280.305(c)(1)(i), increased by a factor of 1.5. The 1.5 factor of safety for Wind Zone I is also to be
applied simultaneously to both the vertical building projection, as horizontal wind load, and across the
surface of the full roof structure, as uplift loading. For Wind Zones II and III, the resistance shall be
determined by the simultaneous application of the horizontal drag and uplift wind loads, in accordance
with § 3280.305(c)(1)(ii). The basic allowable stresses of materials required to resist overturning and
lateral movement shall not be increased in the design and proportioning of these members. No additional
shape or location factors need to be applied in the design of the tiedown system. The dead load of the
structure may be used to resist these wind loading effects in all Wind Zones.
(1) The provisions of this section shall be followed and the support and anchoring systems shall be
designed by a Registered Professional Engineer or Architect.
(2) The manufacturer of each manufactured home is required to make provision for the support and
anchoring systems but is not required to provide the anchoring equipment or stabilizing devices.
When the manufacturer's installation instructions provide for the main frame structure to be used as
the points for connection of diagonal ties, no specific connecting devices need be provided on the
main frame structure.
(b) Contents of instructions.
(1) The manufacturer must provide printed instructions with each manufactured home that specify the
location and required capacity of stabilizing devices on which the home's design is based. The
manufacturer must identify by paint, label, decal stencil, or other means: the location of each column
support pier location required along the marriage line(s) of multi-section manufactured homes; each
pier location required along the perimeter of the home; each required shear wall pier support; and
any other special pier support locations specified in the manufacturer's printed instructions. Such
identifications must be visible after the home is installed. The manufacturer must provide drawings
and specifications, certified by a registered professional engineer or architect, that indicate at least

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one acceptable system of anchoring, including the details or required straps or cables, their end
connections, and all other devices needed to transfer the wind loads from the manufactured home to
an anchoring or foundation system.
(2) For anchoring systems, the instructions shall indicate:
(i)

The minimum anchor capacity required;

(ii) That anchors should be certified by a professional engineer, architect, or a nationally recognized
testing laboratory as to their resistance, based on the maximum angle of diagonal tie and/or
vertical tie loading (see paragraph (c)(3) of this section) and angle of anchor installation, and
type of soil in which the anchor is to be installed;
(iii) That ground anchors are to be embedded below the frost line, unless the foundation system is
frost-protected in accordance with §§ 3285.312(b) and 3285.404 of the Model Manufactured
Home Installation Standards in this chapter.
(iv) That ground anchors must be installed to their full depth, and stabilizer plates must be installed
in accordance with the ground anchor listing or certification to provide required resistance to
overturning and sliding.
(v) That anchoring equipment should be certified by a registered professional engineer or architect
to resist these specified forces in accordance with testing procedures in ASTM D3953-97,
Standard Specification for Strapping, Flat Steel and Seals (incorporated by reference, see §
3280.4).
(c) Design criteria. The provisions made for anchoring systems shall be based on the following design criteria
for manufactured homes.
(1) The minimum number of ties provided per side of each home shall resist design wind loads required
in § 3280.305(c)(1).
(2) Ties shall be as evenly spaced as practicable along the length of the manufactured home, with not
more than two (2) feet open-end spacing on each end.
(3) Vertical ties or straps shall be positioned at studs. Where a vertical tie and a diagonal tie are located
at the same place, both ties may be connected to a single anchor, provided that the anchor used is
capable of carrying both loadings, simultaneously.
(4) Add-on sections of expandable manufactured homes shall have provisions for vertical ties at the
exposed ends.
(d) Requirements for ties. Manufactured homes in Wind Zone I require only diagonal ties. These ties shall be
placed along the main frame and below the outer side walls. All manufactured homes designed to be
located in Wind Zones II and III shall have a vertical tie installed at each diagonal tie location.
(e) Protection requirements. Protection shall be provided at sharp corners where the anchoring system
requires the use of external straps or cables. Protection shall also be provided to minimize damage to
siding by the cable or strap.
(f) Anchoring equipment - load resistance. Anchoring equipment shall be capable of resisting an allowable
working load equal to or exceeding 3,150 pounds and shall be capable of withstanding a 50 percent
overload (4,725 pounds total) without failure of either the anchoring equipment or the attachment point
on the manufactured home.
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(g) Anchoring equipment - weatherization. Anchoring equipment exposed to weathering shall have a
resistance to weather deterioration at least equivalent to that provided by a coating of zinc on steel of not
less than 0.30 ounces per square foot of surface coated, and in accordance with the following:
(1) Slit or cut edges of zinc-coated steel strapping do not need to be zinc coated.
(2) Type 1, Finish B, Grade 1 steel strapping, 11⁄4 inches wide and 0.035 inches in thickness, certified by
a registered professional engineer or architect as conforming with ASTM D3953-97, Standard
Specification for Strapping, Flat Steel and Seals (incorporated by reference, see § 3280.4).
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4583, Feb. 12, 1987; 59 FR 2473,
Jan. 14, 1994; 70 FR 72045, Nov. 30, 2005; 72 FR 59362, Oct. 19, 2007; 78 FR 73983, Dec. 9, 2013]

§ 3280.307 Resistance to elements and use.
(a) Exterior coverings shall be of moisture and weather resistive materials attached with corrosion resistant
fasteners to resist wind, snow and rain. Metal coverings and exposed metal structural members shall be
of corrosion resistant materials or shall be protected to resist corrosion. All joints between portions of the
exterior covering shall be designed, and assembled to protect against the infiltration of air and water,
except for any designed ventilation of wall or roof cavity.
(b) Joints between dissimilar materials and joints between exterior coverings and frames of openings shall
be protected with a compatible sealant suitable to resist infiltration of air or water.
(c) Where adjoining materials or assemblies of materials are of such nature that separation can occur due to
expansion, contraction, wind loads or other loads induced by erection or transportation, sealants shall be
of a type that maintains protection against infiltration or penetration by air, moisture or vermin.
(d) Exterior surfaces shall be sealed to resist the entrance of rodents.
(e) Multi-section and attached manufactured homes (see subpart K of this part) are not required to comply
with the factory installation of weather-resistant exterior finishes for those areas left open for field
connection of the sections provided the following conditions are satisfied:
(1) Temporary weather protection for exposed, unprotected construction is provided in accordance with
methods to be included in the approved design.
(2) Methods for on-site completion and finishing of these elements are included in the approved design.
(3) Complete installation instructions and the required materials for finishing these elements are
provided.
[40 FR 58752, Dec. 18, 1975, as amended at 86 FR 2520, Jan. 12, 2021]

§ 3280.308 Formaldehyde emission controls for composite wood products
(a) Definitions. For purposes of this section, the definitions found in 40 CFR 770.3 apply.
(b) Formaldehyde emission levels. The following maximum formaldehyde emission standards apply whether
the composite wood product is in the form of a panel or is incorporated into a component part or finished
good:
(1) For hardwood plywood made with a veneer core or composite core, the maximum level is 0.05 parts
per million (ppm) of formaldehyde;
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(2) For medium density fiberboard, the maximum level is 0.11 ppm of formaldehyde;
(3) For thin medium density fiberboard, the maximum level is 0.13 ppm of formaldehyde; and
(4) For particleboard, the maximum level is 0.09 ppm of formaldehyde.
(c) Product certification and continuing qualification. Only certified composite wood products whether in the
form of panels or incorporated into component parts or finished goods, are permitted to be used in
manufactured homes sold, supplied, offered for sale, or manufactured in or imported into the United
States, consistent with Environmental Protection Agency (EPA) product testing requirements at 40 CFR
770.15. See § 3280.406 for testing requirements for product certification and testing requirements for
continuing qualification of formaldehyde emission levels.
(d) Panel label. Manufactured homes must use panels or bundles of panels that are labeled by a panel
producer consistent with the labeling requirements at 40 CFR 770.45.
(e) Finished good certification label. Each manufactured home must be provided with a finished good
certification label indicating that the home has been produced with composite wood products, or finished
goods that contain composite wood products, that comply with the formaldehyde emission requirements
of this part and 40 CFR part 770, consistent with § 3280.5(i).
(f) Non-complying lots. Composite wood products from non-complying lots (i.e., lots that exceed the
applicable formaldehyde ppm) are not certified composite wood products and may not be used in
manufactured homes except in accordance with 40 CFR 770.22.
(g) Stockpiling. The use of stockpiled inventory of composite wood products, whether in the form of panels or
incorporated into component parts or finished goods, in manufactured homes, is prohibited in accordance
with EPA regulations at 40 CFR 770.12(b) through (d).
(h) Third party certification. All composite wood products in paragraph (b) of this section must be certified by
an agency or organization that has been recognized to participate in the EPA Toxic Substances Control
Act (TSCA) Title VI Third Party Certification Program.
[85 FR 5566, Jan. 31, 2020]

Subpart E - Testing
§ 3280.401 Structural load tests.
Every structural assembly tested shall be capable of meeting the Proof Load Test or the Ultimate Load Test as
follows:
(a) Proof load tests. Every structural assembly tested must be capable of sustaining its dead load plus
superimposed live loads equal to 1.75 times the required live loads for a period of 12 hours without
failure. Tests must be conducted with loads applied and deflections recorded in 1⁄4 design live load
increments at 10-minute intervals until 1.25 times design live load plus dead load has been reached.
Additional load shall then be applied continuously until 1.75 times design live load plus dead load has
been reached. Assembly failure shall be considered as design live load deflection (or residual deflection
measured 12 hours after live load removal) that is greater than the limits set in § 3280.305(d), rupture,
fracture, or excessive yielding. Design live load deflection criteria do not apply when the structural
assembly being evaluated does not include structural framing members. An assembly to be tested shall
be of the minimum quality of materials and workmanship of the production. Each test assembly,
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component, or subassembly shall be identified as to type and quality or grade of material. All assemblies,
components, or subassemblies qualifying under this test shall be subject to a continuing qualification
testing program acceptable to HUD.
(b) Ultimate load tests. Ultimate load tests must be performed on a minimum of three assemblies or
components to generally evaluate the structural design. Every structural assembly or component tested
must be capable of sustaining its total dead load plus the design live load increased by a factor of safety
of at least 2.5. A factor of safety greater than 2.5 shall be used when required by an applicable reference
standard in § 3280.304(b)(1). Tests shall be conducted with loads applied and deflections recorded in 1/4
design live load increments at 10-minute intervals until 1.25 times design live load plus dead load has
been reached. Additional loading shall then be applied continuously until failure occurs, or the total of the
factor of safety times the design live load plus the dead load is reached. Assembly failure shall be
considered as design live load deflection greater than the limits set in § 3280.305(d), rupture, fracture, or
excessive yielding. Design live load deflection criteria do not apply when the structural assembly being
evaluated does not include structural framing members. Assemblies to be tested shall be representative
of average quality or materials and workmanship of the production. Each test assembly, component, or
subassembly shall be identified as to type and quality or grade of material. All assemblies, components,
or subassemblies qualifying under this test shall be subject to a periodic qualification testing program
acceptable to HUD.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55007, Oct. 25, 1993; 70 FR 72045,
Nov. 30, 2005]

§ 3280.402 Test procedures for roof trusses.
(a) Roof load tests. This section provides the roof truss test procedure for vertical loading conditions. Where
roof trusses act as support for other members, have eave or cornice projections, or support concentrated
loads, roof trusses must also be tested for those conditions. These test procedures are required for new
truss designs in all three wind zones and for existing truss designs used in Wind Zones II and III.
(b) General. Trusses must be tested in a truss test fixture that replicates the design loads, and actual support
points, and does not restrain horizontal movement. When tested singly or in groups of two or more
trusses, trusses shall be mounted on supports and positioned as intended to be installed in the
manufactured home in order to give the required clear span distance (L) and eave or cornice distance
(Lo), if applicable, as specified in the design.
(l) When trusses are tested singly, trusses shall be positioned in a test fixture, with supports properly
located and the roof loads evenly applied. See Figure 3280.402(b)(1).

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(2) When tested in groups of two or more, the top chords are permitted to be sheathed with nominal 1/
4-inch × 12-inch plywood strips. The plywood strips shall be at least long enough to cover the top
chords of the trusses at the designated design truss spacing. Adjacent plywood strips shall be
separated by at least 1/8-inch. The plywood strips shall be nailed with 4d nails or equivalent staples
no closer than 8 inches on center along the top chord. The bottom chords of the adjacent trusses
shall be permitted to be one of the following:
(i)

Unbraced; or

(ii) Laterally braced together (not cross-braced) with 1-inch × 2-inch stripping no closer than 24
inches on center, nailed with only one 8d nail at each truss. See Figure 3280.402(b)(2).

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(c) Measuring and loading methods. Deflections must be measured at the free end of an eave or cornice
projection and at least at the truss mid-span and quarter points. Scissors or other unique truss
configurations are to be measured at as many additional bottom chord panel points as necessary to
obtain an accurate representation of the deflected shape of the truss so as to be able to locate and record
the point(s) of maximum deflection. Deflections must be read and recorded relative to a fixed reference
datum. Deflections must be read and recorded to the nearest 1/32-inch. Dead load must be applied to the
top and bottom chord, and live load must be applied to the top chord through a suitable hydraulic,
pneumatic, or mechanical system or weights to simulate design loads. Load unit weights for uniformly
distributed top chord loads must be separated so that arch action does not occur and be spaced not more
than 12 inches on center so as to simulate uniform loading. Bottom chord loading must be spaced as
uniformly as practical. Truss gravity loads must be calculated based on the overall truss length (horizontal
projection), including eave or cornice projections.
(d) Testing procedures. Either the testing method in paragraph (d)(1) or (d)(2) of this section may be used,
however, the testing method in paragraph (d)(3) of this section must be used, to test trusses to establish
compliance with the provisions of these standards.
(1) Proof load truss test procedure. At least three average quality/consecutively tested trusses must
pass all requirements of the test, for initial qualification of the truss design. All tests for initial
qualification of the truss designs evaluated by this procedure must be certified by a Registered
Engineer or Architect, or by a nationally recognized testing laboratory. An in-house quality control
and follow-up testing program (see paragraphs (e) and (f) of this section) must be approved prior to
entering production of any truss design evaluated by this procedure.
(i)

Dead load. Measure and record initial elevation of the truss or trusses in the test position at no
load. Apply to the top and bottom chords of the truss dead loads that are representative of the
actual weights of materials to be supported by the truss. However, the dead load may only be
applied as indicated in paragraph (e)(4) of this section for ongoing follow-up testing. Dead
loads to be applied to the truss test assembly are permitted to include only the weights of
materials supported by the truss and not the weight of the truss itself. However, readings from

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load cells (when used) on which the test truss rests must reflect the sum of the applied load
plus the weight of the truss. Apply dead loads and hold for 5 minutes. Measure and record the
deflections.
(ii) Live load. Maintaining the dead loads, apply live load to the top chord in approximate 1⁄4 live
load increments until dead load plus the live load is reached. Measure and record the
deflections no sooner than one minute after each 1⁄4 live load increment has been applied and 5
minutes after the full live load has been reached.
(iii) Initial recovery phase. Remove the design live load but not the dead load. Measure and record
the deflections 5 minutes after the total live load has been removed.
(iv) Continue to load the truss to:
(A) Dead load plus 2.0 times the design live load. Maintain this loading for 6 hours and inspect
the truss for failure. Failure is rupture, fracture, or excessive yielding; or
(B) Dead load plus 1.75 times the design live load. Maintain this loading for 12 hours and
inspect the truss for failure. Failure is rupture, fracture, or excessive yielding.
(v) Final recovery phase. Remove 2.0 times the design live load, but not the dead load or 1.75 times
the design live load, but not the dead load. Measure and record deflections within 4 hours after
removing 2.0 times the design live load or 1.75 times the design live load.
(vi) Acceptance criteria. The truss design is acceptable if all of the following conditions are met:
(A) The maximum deflection between no load and dead load must be L/480 or less for simply
supported clear spans and Lo/180 or less for eave and cornice projections; and
(B) The maximum deflection between dead load and design live load must be L/180 or less
for simply supported clear spans and Lo/90 or less for eave and cornice projections; and
(C) After the design live load is removed, and with the dead load still applied, the maximum
recovery deflection must be L/360 or less for simply supported spans and Lo/180 or less
for eave and cornice projections; and
(D) The truss must maintain the overload condition for 6 hours without rupture or fracture, or
excessive yielding; and
(E) After 2.0 times the design live load has been removed, and with the dead load still applied,
the maximum recovery deflection must be L/180 or less for simply supported clear spans
and Lo/90 or less for eave and cornice projections; and
(F) As applicable, each truss design must also meet all requirements for uplift loads required
by paragraph (d)(3) of this section. For Wind Zone I uplift load requirements, see
paragraph (d)(3)(i) of this section. For Wind Zones II and III uplift load requirements, see
paragraph (d)(3)(ii) of this section.
(2) Ultimate load truss test procedure.
(i)

At least two average quality/consecutively tested trusses must pass all requirements of the
test, for initial qualification of the truss design. All tests for initial qualification of the truss
designs evaluated by this procedure must be certified by a Registered Engineer or Architect, or

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by a nationally recognized testing laboratory. An in-house quality control and follow-up testing
program (see paragraph (e) and (f) of this section) must be approved prior to entering
production of any truss design evaluated by this procedure.
(ii) Dead load. Measure and record initial elevation of the truss or trusses in the test position at no
load. Apply to the top and bottom chords of the truss dead loads that are representative of the
actual weights of materials to be supported by the truss. However, the dead load may only be
applied as indicated in paragraph (e)(4) of this section for ongoing follow-up testing. Dead
loads to be applied to the truss test assembly shall be permitted to include only the weights of
materials supported by the truss, and not the weight of the truss itself. However, readings from
load cells (when used) on which the test truss rests must reflect the sum of the applied load
plus the weight of the truss. Apply dead loads and hold for 5 minutes. Measure and record the
deflections.
(iii) Live load. Maintaining the dead loads, apply live load at a uniform rate to the top chord in
approximate 1⁄4 live load increments until the dead load plus the live load is reached. Measure
and record the deflections no sooner than one minute after each 1⁄4 live load increment has
been applied and 5 minutes after the full live load has been reached.
(iv) Initial recovery phase. Remove the design live load but not the dead load. Measure and record
the deflections 5 minutes after the design live load has been removed.
(v) Overload phase. After the recovery phase is completed, reapply the full live load to the truss
assembly. Additional loading shall then be applied continuously until the dead load plus 2.5
times the design live load is reached. This overload condition must be maintained for at least 5
minutes.
(vi) Final recovery phase. Remove 2.5 times the design live load but not the dead load. Measure and
record deflections within 4 hours after 2.5 times the design live load has been removed.
(vii) Acceptance criteria. The truss design is acceptable if all of the following conditions are met:
(A) The maximum deflection between no load and dead load must be L/480 or less for simply
supported clear spans and Lo/180 or less for eave and cornice projections; and
(B) Dead load to design live load deflections shall be L/180 or less for simply supported clear
spans and Lo/90 or less for eave and cornice projections; and
(C) After the design live load is removed and with the dead load still applied, the maximum
recovery deflection must be L/360 or less for simply supported spans and Lo/180 or less
for eave and cornice projections; and
(D) The truss shall maintain the overload condition for 5 minutes without rupture, fracture, or
excessive yielding; and
(E) After 2.5 times the design live load is removed, and with the dead load still applied, the
truss must recover to at least L/180 for simply supported clear spans and Lo/90 for eave
and cornice within 4 hours after the total live load has been removed; and
(F) As applicable, each truss design must also meet all requirements for uplift loads in Wind
Zone I or Wind Zone II and III, as required by paragraph (d)(3) of this section. For Wind
Zone I uplift load requirements, see paragraph (d)(3)(i) of this section. For Wind Zones II
and III uplift load requirements, see paragraph (d)(3)(ii) of this section.
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(3) Uplift load tests. Each truss design must also pass all requirements of the uplift load test, as
applicable, in paragraph (d)(3)(i) or (d)(3)(ii) and paragraphs (d)(3)(iii) and (d)(3)(iv) of this section.
(i)

Wind Zone I uplift load test. Where there are engineered connectors between the top chord and
web members of the truss, such as metal connector plates or wood gussets or their
equivalents, uplift testing in Wind Zone I is at the discretion of the Registered Engineer or
Architect or nationally recognized testing laboratory certifying the truss design. When testing is
deemed necessary by the Registered Engineer or Architect or nationally recognized testing
laboratory certifying the truss design, a minimum of one average quality uplift load test is to be
conducted for each such truss design and must pass all requirements of the test for initial
qualification of the truss design. The net uplift load for trusses designed for use in Wind Zone I
is 9 psf for the clear span of the truss and 22.5 psf for eave or cornice projections.

(ii) Wind Zones II and III uplift loads test. This test is required for all trusses designed for use in
Wind Zones II and III. A minimum of three average quality/consecutive uplift load tests are to
be conducted for each truss design when tested in the inverted position and a minimum of two
average quality/consecutive uplift load tests are to be conducted for trusses in the upright
position. The trusses must pass all requirements of the test for initial qualification of the truss
design. The uplift load for trusses designed to be used in Wind Zones II and III for the clear
span or eave cornice projections is to be determined by subtracting the dead load applied to the
truss from the uplift load provided in the Table of Design Wind Pressures in §
3280.305(c)(1)(ii)(B).
(iii) Trusses designed for use in Wind Zone I, when tested (see paragraph (d)(3)(i) of this section),
must be tested in either the inverted position to 2.5 times the net wind uplift load or in the
upright position to 1.75 times the net wind uplift load. Trusses designed for use in Wind Zones
II and III (see paragraph (d)(3)(ii) of this section) must be tested to 2.0 times the uplift load
minus the dead load in the inverted position and to 1.75 times the uplift load minus the dead
load in the upright position. See Figure 3280.402(b)(3).
(iv) The following describes how to conduct the uplift test with the truss in the upright position.
Similar procedures must be used if conducting the test in the inverted position.
(A) Place the truss in the test fixture and position as it is intended to be installed in the
manufactured home. See Figure 3280.402(b)(3).

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(B) Position the load measurement devices to register the wind uplift loads that will be applied
to the top chord of the truss. The uplift loads shall be applied through tension devices not
wider than one inch and spaced not greater than approximately 12 inches on center and
shall be applied as uniform as possible, so as to simulate uniform loading. Gravity and
wind uplift load tests may be performed on the same truss in this single setup mode. For
the wind uplift test, it is permissible to stabilize the bottom chord of the truss in the test
fixture to simulate ceiling materials or purlin supports. Measure and record the initial
elevation of the bottom chord of the truss in the test position at the mid-span and quarter
points of the truss, and at the free end of an eave or cornice projection greater than 12
inches. Scissors or other unique truss configurations are to be measured at as many
additional bottom chord panel points as necessary to obtain an accurate representation of
the deflected shape of the truss, so as to be able to locate and record the point(s) of
maximum deflection. Eave or cornice projection loads are applied separately for eaves or
cornice projections greater than 12 inches. For eave or cornice projections greater than 12
inches, the additional required load must be applied to the eave simultaneously with the
main body load. For eave or cornice projections of 12 inches or less, add the additional
required load to the main body load and apply it to the entire top chord.

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(C) Measure and record the deflection 5 minutes after the net uplift load has been applied.
Design load deflection shall be L/180 or less for a simply supported clear span and Lo/90
or less for eave or cornice projections.
(D) For trusses tested in the upright position, continue to load the truss to 1.75 times the net
uplift load in paragraph (d)(3)(i) of this section for Wind Zone I and 1.75 times the uplift
load in paragraph (d)(3)(ii) for Wind Zones II and III, and maintain the load for one minute.
For trusses tested in the inverted position, continue to load the truss to 2.50 times the net
uplift load in paragraph (d)(3)(i) for Wind Zone I and to 2.0 times the uplift load minus the
dead load in paragraph (d)(3)(ii) for Wind Zones II and III, and maintain the full load for one
minute. Regardless of the test position of the truss, upright or inverted, trusses must
maintain the overload for the specified time period without rupture, fracture, or excessive
yielding.
(e) Follow-up testing. Follow-up testing procedures must include the following:
(1) All trusses qualifying under these test procedures must be subject to a quality control and follow-up
testing program.
(i)

Manufacturers of listed or labeled trusses must follow an in-house quality control program with
follow-up testing approved by a nationally recognized testing program as specified in paragraph
(e)(3) of this section. The in-house quality control program must include, at a minimum,
procedures for quality of materials including, but not limited to, grade(s) of materials, allowable
splits, knots, and other applicable lumber qualities; workmanship including, but not limited to,
plate placement and embedment tolerances; other manufacturing tolerances; description and
calibration of test equipment; truss retesting criteria; and procedures in the event of
noncomplying results.

(ii) Those home manufacturers producing trusses for their own use, and which are not listed or
labeled, must have an in-house quality control program (see paragraph (i) of this section) that
includes follow-up testing, as specified in this section, and is approved by their Design Approval
Primary Inspection Agency (DAPIA).
(2) Truss designs that are qualified but not in production are not subject to follow-up testing until
produced. When the truss design is brought into production, a follow-up test is to be performed if the
truss design has been out of production for more than 6 months.
(3) The frequency of truss manufacturer's quality control follow-up testing for trusses must be at least:
(i)

One test for the first 100 trusses produced, with a subsequent test for every 2,500 trusses for
trusses qualified under the proof load truss test procedure or inverted uplift test procedure for
trusses used in Wind Zones II and III or once every 6 months, whichever is more frequent, for
every truss design produced; or

(ii) One test for every 4,000 trusses produced for trusses qualified under the ultimate load truss
test procedure or upright uplift test procedure for trusses used in Wind Zones II and III or once
every 6 months, whichever is more frequent, for every truss design produced.
(4) For follow-up testing only, the full dead load may be applied to the top chord of the truss, when the
bottom chord dead load is 5 psf or less.
[78 FR 4065, Jan. 18, 2013]
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24 CFR 3280.403

§ 3280.403 Requirements for windows, sliding glass doors, and skylights.
(a) Scope. This section establishes the requirements for prime windows and sliding glass doors, except that
windows used in an entry door are components of the door and are excluded from these requirements.
(b)
(1) Standard. All primary windows and sliding glass doors shall comply with AAMA 1701.2-95, Voluntary
Standard Primary Window and Sliding Glass Door for Utilization in Manufactured Housing, except the
exterior and interior pressure tests must be conducted at the design wind loads required for
components and cladding specified in § 3280.305(c)(1).
(2) All skylights must comply with AAMA/WDMA/CSA/101/I.S.2/A440-08: North American Fenestration
Standard/Specifications for Windows, Doors and Skylights (incorporated by reference, see § 3280.4).
Skylights must withstand the roof loads for the applicable Roof Load Zone specified in §
3280.305(c)(3), and the following wind loads:
(i)

For Wind Zone I, the wind loads specified in § 3280.305(c)(1)(i); and

(ii) For Wind Zones II and III, the wind loads specified for exterior roof coverings, sheathing, and
fastenings in § 3280.305(c)(1)(ii).
(c) Installation. All primary windows, sliding glass doors, and skylights must be installed in a manner that
allows proper operation and provides protection against the elements, as required by § 3280.307.
(d) Glass.
(1) Safety glazing materials, where used shall meet Standard for Safety Glazing Materials used in
Buildings - Safety Performance Specifications and Methods of Test, ANSI Z97.1-2004 (incorporated
by reference, see § 3280.4).
(2) Sealed insulating glass, where used, must meet all performance requirements for Class C in
accordance with ASTM E 774-97, Standard Specification for the Classification of the Durability of
Sealed Insulating Glass Units. The sealing system must be qualified in accordance with ASTM E
773-97, Standard Test Methods for Accelerated Weathering of Sealed Insulating Glass Units. Each
glass unit must be permanently identified with the name of the insulating glass manufacturer.
(e) Certification. All primary windows and sliding glass doors to be installed in manufactured homes must be
certified as complying with AAMA 1701.2-95. This certification must be based on tests conducted at the
design wind loads specified in § 3280.305(c)(1).
(1) All such windows and doors must show evidence of certification by affixing a quality certification
label to the product in accordance with ANSI Z34.1-1993, Third-Party Certification Programs for
Products, Processes, and Services.
(2) In determining certifiability of the products, an independent quality assurance agency shall conduct
pre-production specimen tests in accordance with AAMA 1701.2-95. Further, such agency must
inspect the product manufacturer's facility at least twice per year.
(3) All skylights installed in manufactured homes must be certified as complying with AAMA/WDMA/
CSA 101/I.S.2/A440-08: North American Fenestration Standard/Specifications for Windows, Doors,
and Skylights (incorporated by reference, see § 3280.4). This certification must be based on
applicable loads specified in paragraph (b) of this section.

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24 CFR 3280.403(f)

(f) Protection of primary window and sliding glass door openings in high wind areas. For homes designed to
be located in Wind Zones II and III, manufacturers shall design exterior walls surrounding the primary
window and sliding glass door openings to allow for the installation of shutters or other protective covers,
such as plywood, to cover these openings. Although not required, the Department encourages
manufacturers to provide the shutters or protective covers and to install receiving devices, sleeves, or
anchors for fasteners to be used to secure the shutters or protective covers to the exterior walls. If the
manufacturer does not provide shutters or other protective covers to cover these openings, the
manufacturer must provide to the homeowner instructions for at least one method of protecting primary
window and sliding glass door openings. This method must be capable of resisting the design wind
pressures specified in § 3280.305 without taking the home out of conformance with the standards in this
part. These instructions must be included in the printed instructions that accompany each manufactured
home. The instructions shall also indicate whether receiving devices, sleeves, or anchors, for fasteners to
be used to secure the shutters or protective covers to the exterior walls, have been installed or provided
by the manufacturer.
[52 FR 4583, Feb. 12, 1987, as amended at 52 FR 35543, Sept. 22, 1987; 58 FR 55009, Oct. 25, 1993; 59 FR 2474, Jan. 14, 1994;
70 FR 72046, Nov. 30, 2005; 78 FR 73983, Dec. 9, 2013]

§ 3280.404 Standard for egress windows and devices for use in manufactured homes.
(a) Scope and purpose. The purpose of this section is to establish the requirements for the design,
construction, and installation of windows and approved devices intended to be used as an emergency exit
during conditions encountered in a fire or similar disaster.
(b) Performance. Egress windows including auxiliary frame and seals, if any, shall meet all requirements of
AAMA 1701.2-95, Voluntary Standard Primary Window and Sliding Glass Door for Utilization in
Manufactured Housing and AAMA Standard 1704-1985, Voluntary Standard Egress Window Systems for
Utilization in Manufactured Housing, except the exterior and interior pressure tests for components and
cladding must be conducted at the design wind loads required by § 3280.305(c)(1).
(c) Installation.
(1) The installation of egress windows or devices shall be installed in a manner which allows for proper
operation and provides protection against the elements. (See § 3280.307.)
(2) An operational check of each installed egress window or device must be made at the manufactured
home factory. All egress windows and devices must be capable of being opened to the minimum
required dimensions by normal operation of the window without binding or requiring the use of tools.
Any window or device failing this check must be repaired or replaced. A repaired window must
conform to its certification. Any repaired or replaced window or device must pass the operational
check.
(3) Windows that require the removal of the sash to meet egress size requirements are prohibited.
(d) Operating instructions. Operating instructions shall be affixed to each egress window and device and carry
the legend “Do Not Remove.”
(e) Certification of egress windows and devices. Egress windows and devices shall be listed in accordance
with the procedures and requirements of AAMA Standard 1704-1985. As of January 17, 1995, this
certification must be based on tests conducted at the design wind loads specified in § 3280.305(c)(1).

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24 CFR 3280.404(f)

(f) Protection of egress window openings in high wind areas. For homes designed to be located in Wind
Zones II and III, manufacturers shall design exterior walls surrounding the egress window openings to
allow for the installation of shutters or other protective covers, such as plywood, to cover these openings.
Although not required, the Department encourages manufacturers to provide the shutters or protective
covers and to install receiving devices, sleeves, or anchors for fasteners to be used to secure the shutters
or protective covers to the exterior walls. If the manufacturer does not provide shutters or other protective
covers to cover these openings, the manufacturer must provide to the homeowner instructions for at least
one method of protecting egress window openings. This method must be capable of resisting the design
wind pressures specified in § 3280.305 without taking the home out of conformance with the standards
in this part. These instructions must be included in the printed instructions that accompany each
manufactured home. The instructions shall also indicate whether receiving devices, sleeves, or anchors,
for fasteners to be used to secure the shutters or protective covers to the exterior walls, have been
installed or provided by the manufacturer.
[52 FR 4583, Feb. 12, 1987, as amended at 59 FR 2474, Jan. 14, 1994; 70 FR 72046, Nov. 30, 2005; 78 FR 73983, Dec. 9, 2013]

§ 3280.405 Standard for swinging exterior passage doors for use in manufactured homes.
(a) Introduction. This standard applies to all exterior passage door units, excluding sliding doors and doors
used for access to utilities and compartments. This standard applies only to the door frame consisting of
jambs, head and sill and the attached door or doors.
(b) Performance requirements. The design and construction of exterior door units must meet all requirements
of AAMA 1702.2-95, Voluntary Standard Swinging Exterior Passage Door for Utilization in Manufactured
Housing.
(c) Materials and methods. Any material or method of construction shall conform to the performance
requirements as outlined in paragraph (b) of this section. Plywood shall be exterior type and preservative
treated in accordance with NWWDA I.S.4-81, Water Repellent Preservative Non-Pressure Treatment for
Millwork.
(d) Exterior doors. All swinging exterior doors shall be installed in a manner which allows proper operation
and provides protection against the elements (see § 3280.307).
(e) Certification. All swinging exterior doors to be installed in manufactured homes must be certified as
complying with AAMA 1702.2-95, Voluntary Standard Swinging Exterior Passage Door for Utilization in
Manufactured Housing.
(1) All such doors must show evidence of certification by affixing a quality certification label to the
product in accordance with ANSI Z34.1-1993, Third Party Certification Programs for Products,
Processes, and Services.
(2) In determining certifiability of the products, an independent quality assurance agency must conduct
a pre-production specimen test in accordance with AAMA 1702.2-95, Voluntary Standard Swinging
Exterior Passage Door for Utilization in Manufactured Housing.
(f) Protection of exterior doors in high wind areas. For homes designed to be located in Wind Zones II and III,
manufacturers shall design exterior walls surrounding the exterior door openings to allow for the
installation of shutters or other protective covers, such as plywood, to cover these openings. Although not
required, the Department encourages manufacturers to provide the shutters or protective covers and to
install receiving devices, sleeves, or anchors for fasteners to be used to secure the shutters or protective
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24 CFR 3280.406

covers to the exterior walls. If the manufacturer does not provide shutters or other protective covers to
cover these openings, the manufacturer must provide to the homeowner instructions for at least one
method of protecting exterior door openings. This method must be capable of resisting the design wind
pressures specified in § 3280.305 without taking the home out of conformance with the standards in this
part. These instructions must be included in the printed instructions that accompany each manufactured
home. The instructions shall also indicate whether receiving devices, sleeves, or anchors, for fasteners to
be used to secure the shutters or protective covers to the exterior walls, have been installed or provided
by the manufacturer.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4583, Feb. 12, 1987; 52 FR 35543,
Sept. 22, 1987; 58 FR 55009, Oct. 25, 1993; 59 FR 2474, Jan. 14, 1994; 70 FR 72046, Nov. 30, 2005]

§ 3280.406 Air chamber test methods for certification and continuing qualification of
formaldehyde emission levels.
(a) Definitions. For purposes of this section, the definitions found in 40 CFR 770.3 apply.
(b) Testing requirements. Testing of composite wood products must be performed pursuant to the general
requirements of 40 CFR 770.20(a) and (b). Certification testing must be performed pursuant to one of the
air chamber test methods specified in 40 CFR 770.15 (ASTM E1333-14, or ASTM D6007-14, both
incorporated by reference, see § 3280.4). Quarterly testing must be performed pursuant to one of the air
chamber test methods specified in 40 CFR 770.20(c) (ASTM E1333-14 or ASTM D6007-14).
(c) Samples for testing. Samples for testing shall comply with 40 CFR 770.24.
[85 FR 5566, Jan. 31, 2020]

§ 3280.407 Quality control testing, manuals, facilities, and personnel.
(a) Definitions. For purposes of this section, the definitions found in 40 CFR 770.3 apply.
(b) Quality control testing. Quality control testing is required for hardwood plywood made with a veneer core
or composite core, medium density fiberboard, thin medium density fiberboard, and particleboard and
must be performed in accordance with the general requirements in 40 CFR 770.20(a) and by one of the
test methods and at the frequency specified in 40 CFR 770.20(b). Panels being tested with an equivalence
and correlation must be determined in accordance with 40 CFR 770.20(d).
(c) Quality control manuals, facilities, and personnel. A panel producer must have a written quality control
manual, must designate a quality control facility for conducting quality control formaldehyde testing
under this section, and must designate a person as quality control manager with adequate experience
and/or training to be responsible for formaldehyde emissions quality control consistent with 40 CFR
770.21. A panel producer means a manufacturing plant or other facility that manufactures (excluding
facilities that solely import products) composite wood products (hardwood plywood made with a veneer
or composite core, medium-density fiberboard, and particleboard) on the premises.
[85 FR 5566, Jan. 31, 2020]

Subpart F - Thermal Protection

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24 CFR 3280.501

§ 3280.501 Scope.
This subpart sets forth the requirements for condensation control, air infiltration, thermal insulation and certification
for heating and comfort cooling.

§ 3280.502 Definitions.
(a) The following definitions are applicable to subpart F only:
(1) Pressure envelope means that primary air barrier surrounding the living space which serves to limit
air leakage. In construction using ventilated cavities, the pressure envelope is the interior skin.
(2) Thermal envelope area means the sum of the surface areas of outside walls, ceiling and floor,
including all openings. The wall area is measured by multiplying outside wall lengths by the inside
wall height from floor to ceiling. The floor and ceiling areas are considered as horizontal surfaces
using exterior width and length.

§ 3280.503 Materials.
Materials used for insulation shall be of proven effectiveness and adequate durability to assure that required design
conditions concerning thermal transmission are attained.

§ 3280.504 Condensation control and installation of vapor retarders.
(a) Ceiling vapor retarders.
(1) In Uo Value Zones 2 and 3, ceilings must have a vapor retarder with a permeance of not greater than
1 perm (as measured by ASTM E 96-95 Standard Test Methods for Water Vapor Transmission of
Materials) (incorporated by reference, see § 3280.4) installed on the living space side of the roof
cavity.
(2) For manufactured homes designed for Uo Value Zone 1, the vapor retarder may be omitted.
(3) In multi-story manufactured homes, the ceiling vapor retarder is permitted to be omitted when the
story directly above is part of the same manufactured home.
(b) Exterior walls. Exterior walls must be provided with a system or method to manage moisture and vapor
accumulation with one of the elements in paragraphs (b)(1) through (4) of this section. For purposes of
the requirement in this paragraph (b), the fire separation wall between each attached manufactured home
must be considered to be an exterior wall. See subpart K of this part.
(1) Exterior walls shall have a vapor barrier no greater than 1 perm (dry cup method) installed on the
living space side of the wall, or
(2) Unventilated wall cavities must have an external covering and/or sheathing that forms the pressure
envelope. The covering and/or sheathing must have a combined permeance of not less than 5.0
perms. In the absence of test data, combined permeance is permitted to be computed using the
following formula: P total = (1/[(1/P1) + (1/P2)]), where P1 and P2 are the permeance values of the
exterior covering and sheathing in perms. Formed exterior siding applied in sections with joints not
caulked or sealed, are not considered to restrict water vapor transmission; or
(3) Wall cavities must be constructed so that ventilation is provided to dissipate any condensation
occurring in these cavities; or
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24 CFR 3280.504(b)(4)

(4) Homes manufactured to be sited in “humid climates” or “fringe climates” as shown on the Humid
and Fringe Climate Map in this paragraph are permitted to have a vapor retarder specified in
paragraph (b)(1) of this section installed on the exterior side of the wall insulation or be constructed
with an external covering and sheathing with a combined permeance of not greater than 1.0 perms,
provided the interior finish and interior wall panel materials have a combined permeance of not less
than 5.0 perms. The following need not meet the minimum combined permeance rating of not less
than 5.0 perms for interior finish or wall panel materials:
(i)

Kitchen back splash materials, less than 50 square feet in area installed around countertops,
sinks, and ranges;

(ii) Bathroom tub areas, shower compartments;
(iii) Cabinetry and built-in furniture;
(iv) Trim materials;
(v) Hardboard wall paneling of less than 50 square feet in area under chair rails.

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24 CFR 3280.504(b)(5)

(5) The following areas of local governments (counties or similar areas, unless otherwise specified),
listed by state are deemed to be within the humid and fringe climate areas shown on the Humid and
Fringe Climate Map in paragraph (b)(4) of this section, and the vapor retarder or construction
methods specified in paragraph (b)(4) of this section may be applied to homes built to be sited
within these jurisdictions:

Alabama
Baldwin, Barbour, Bullock, Butler, Choctaw, Clarke, Coffee, Conecuh, Covington, Crenshaw, Dale, Escambia,
Geneva, Henry, Houston, Lowndes, Marengo, Mobile, Monroe, Montgomery, Pike, Washington, Wilcox.

Florida
All counties and locations within the State of Florida.

Georgia
Appling, Atkinson, Bacon, Baker, Ben Hill, Berrien, Brantley, Brooks, Bryan, Calhoun, Camden, Charlton,
Chatham, Clay, Clinch, Coffee, Colquitt, Cook, Crisp, Decatur, Dougherty, Early, Echols, Effingham, Evans,
Glynn, Wayne, Grady, Irwin, Jeff Davis, Lanier, Lee, Liberty, Long, Lowndes, McIntosh, Miller, Mitchell,
Pierce, Quitman, Randolph, Seminole, Tattnall, Terrell, Thomas, Tift, Turner, Ware, Worth.

Hawaii
All counties and locations within the State of Hawaii.

Louisiana
All counties and locations within the State of Louisiana.

Mississippi
Adams, Amite, Claiborne, Clarke, Copiah, Covington, Forrest, Franklin, George, Greene, Hancock, Harrison,
Hinds, Issaquena, Jackson, Jasper, Jefferson, Jefferson Davis, Jones, Lamar, Lawrence, Lincoln, Marion,
Pearl River, Perry, Pike, Rankin, Simpson, Smith, Stone, Walthall, Warren, Wayne, Wilkinson.

North Carolina
Brunswick, Carteret, Columbus, New Hanover, Onslow, Pender.

South Carolina
Jasper, Beaufort, Colleton, Dorchester, Charleston, Berkeley, Georgetown, Horry.

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24 CFR 3280.504(c)

Texas
Anderson, Angelina, Aransas, Atascosa, Austin, Bastrop, Bee, Bexar, Brazoria, Brazos, Brooks, Burleson,
Caldwell, Calhoun, Cameron, Camp, Cass, Chambers, Cherokee, Colorado, Comal, De Witt, Dimmit, Duval,
Falls, Fayette, Fort Bend, Franklin, Freestone, Frio, Galveston, Goliad, Gonzales, Gregg, Grimes, Guadalupe,
Hardin, Harris, Harrison, Hays, Henderson, Hidalgo, Hopkins, Houston, Jackson, Jasper, Jefferson, Jim
Hogg, Jim Wells, Karnes, Kaufman, Kennedy, Kinney, Kleberg, La Salle, Lavaca, Lee, Leon, Liberty,
Limestone, Live Oak, Madison, Marion, Matagorda, Maverick, McMullen, Medina, Milam, Montgomery,
Morris, Nacogdoches, Navarro, Newton, Nueces, Orange, Panola, Polk, Rains, Refugio, Robertson, Rusk,
Sabine, San Augustine, San Jacinto, San Patricio, Shelby, Smith, Starr, Titus, Travis, Trinity, Tyler, Upshur,
Uvalde, Val Verde, Van Zandt, Victoria, Walker, Waller, Washington, Webb, Wharton, Willacy, Williamson,
Wilson, Wood, Zapata, Zavala.
(c) Liquid applied vapor retarders. Each liquid applied vapor retarder must be tested by a nationally
recognized testing agency for use on the specific substrate to which it is applied. The test report must
include the perm rating, as measured by ASTM E 96-95, Standard Test Methods for Water Vapor
Transmission of Materials, and associated application rate for each specific substrate.
(d) Attic or roof ventilation.
(1) Attic and roof cavities shall be vented in accordance with one of the following:
(i)

A minimum free ventilation area of not less than 1/300 of the attic or roof cavity floor area. At
least 50 percent of the required free ventilation area shall be provided by ventilators located in
the upper portion of the space to be ventilated. At least 40 percent shall be provided by eave,
soffit or low gable vents. The location and spacing of the vent openings and ventilators shall
provide cross-ventilation to the entire attic or roof cavity space. A clear air passage space
having a minimum height of 1 inch shall be provided between the top of the insulation and the
roof sheathing or roof covering. Baffles or other means shall be provided where needed to
insure the 1 inch height of the clear air passage space is maintained.

(ii) A mechanical attic or roof ventilation system may be installed instead of providing the free
ventilation area when the mechanical system provides a minimum air change rate of 0.02 cubic
feet per minute (cfm) per sq. ft. of attic floor area. Intake and exhaust vents shall be located so
as to provide air movement throughout space.
(2) Single section manufactured homes constructed with metal roofs and having no sheathing or
underlayment installed, are not required to be provided with attic or roof cavity ventilation provided
that the air leakage paths from the living space to the roof cavity created by electrical outlets,
electrical junctions, electrical cable penetrations, plumbing penetrations, flue pipe penetrations and
exhaust vent penetrations are sealed.
(3) Parallel membrane roof section of a closed cell type construction are not required to be ventilated.
(4) The vents provided for ventilating attics and roof cavities shall be designed to resist entry of rain and
insects.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55009, Oct. 25, 1993; 70 FR 72046,
Nov. 30, 2005; 71 FR 19639, Apr. 17, 2006; 78 FR 73984, Dec. 9, 2013; 86 FR 2521, Jan. 12, 2021]

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24 CFR 3280.505

§ 3280.505 Air infiltration.
(a) Envelope air infiltration. The opaque envelope shall be designed and constructed to limit air infiltration to
the living area of the home. Any design, material, method or combination thereof which accomplishes this
goal may be used. The goal of the infiltration control criteria is to reduce heat loss/heat gain due to
infiltration as much as possible without impinging on health and comfort and within the limits of
reasonable economics.
(1) Envelope penetrations. Plumbing, mechanical and electrical penetrations of the pressure envelope
not exempted by this part, and installations of window and door frames shall be constructed or
treated to limit air infiltration. Penetrations of the pressure envelope made by electrical equipment,
other than distribution panel boards and cable and conduit penetrations, are exempt from this
requirement. Cable penetrations through outlet boxes are considered exempt.
(2) Joints between major envelope elements. Joints not designed to limit air infiltration between wall-towall, wall-to-ceiling and wall-to-floor connections shall be caulked or otherwise sealed. When walls
are constructed to form a pressure envelope on the outside of the wall cavity, they are deemed to
meet this requirement.

§ 3280.506 Heat loss/heat gain.
(a) The manufactured home heat loss/heat gain shall be determined by methods outlined in §§ 3280.508 and
3280.509. The Uo (Coefficient of heat transmission) value zone for which the manufactured home is
acceptable and the lowest outdoor temperature to which the installed heating equipment will maintain a
temperature of 70 F shall be certified as specified in § 3280.510. The Uo value zone shall be determined
from the map in figure 1 to this paragraph (a).
Figure 1 to Paragraph (a)

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24 CFR 3280.506(b)

(b) The overall coefficient of heat transmission (Uo) of the manufactured home for the respective zones and
an indoor design temperature of 70 F, including internal and external ducts, and excluding infiltration,
ventilation, and condensation control, shall not exceed the Btu/(hr.) (sq. ft.) (F) of the manufactured home
envelope are as tabulated in the table to this paragraph (b):

Table 1 to Paragraph (b)
Uo value zone

Maximum coefficient of heat transmission

1

0.116 Btu/(hr.) (sq. ft.) (F).

2

0.096 Btu/(hr.) (sq. ft.) (F).

3

0.079 Btu/(hr.) (sq. ft.) (F).

(c) To assure uniform heat transmission in manufactured homes, cavities in exterior walls, floors, and ceilings
must be provided with thermal insulation. For insulation purposes, the fire separation wall between each
single family attached manufactured home shall be considered an exterior wall (see subpart K of this
part).
(d) Manufactured homes designed for Uo Value Zone 3 shall be factory equipped with storm windows or
insulating glass.
[58 FR 55009, Oct. 25, 1993; 59 FR 15113, Mar. 31, 1994; 86 FR 2521, Jan. 12, 2021]

§ 3280.507 Comfort heat gain.
Information necessary to calculate the home cooling load shall be provided as specified in this part.
(a) Transmission heat gains. Homes complying with this section shall meet the minimum heat loss
transmission coefficients specified in § 3280.506(a).

§ 3280.508 Heat loss, heat gain and cooling load calculations.
(a) Information, values and data necessary for heat loss and heat gain determinations must be taken from
the 1997 ASHRAE Handbook of Fundamentals, Inch-Pound Edition, chapters 22 through 27. The following
portions of those chapters are not applicable:
23.1 Steel Frame Construction
23.2 Masonry Construction
23.3 Foundations and Floor Systems
23.15 Pipes
23.17 Tanks, Vessels, and Equipment
23.18 Refrigerated Rooms and Buildings
24.18 Mechanical and Industrial Systems
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24 CFR 3280.508(b)

25.19 Commercial Building Envelope Leakage
27.9 Calculation of Heat Loss from Crawl Spaces
(b) The calculation of the manufactured home's transmission heat loss coefficient (Uo) must be in
accordance with the fundamental principles of the 1997 ASHRAE Handbook of Fundamentals, Inch-Pound
Edition, and, at a minimum, must address all the heat loss or heat gain considerations in a manner
consistent with the calculation procedures provided in the document, Overall U-values and Heating/
Cooling Loads - Manufactured Homes - February 1992-PNL 8006, HUD User No. 0005945.
(c) Areas where the insulation does not fully cover a surface or is compressed shall be accounted for in the Ucalculation (see § 3280.506). The effect of framing on the U-value must be included in the Uo calculation.
Other low-R-value heat-flow paths (“thermal shorts”) shall be explicitly accounted for in the calculation of
the transmission heat loss coefficient if in the aggregate all types of low-R-value paths amount to more
than 1% of the total exterior surface area. Areas are considered low-R-value heat-flow paths if:
(1) They separate conditioned and unconditioned space; and
(2) They are not insulated to a level that is at least one-half the nominal insulation level of the
surrounding building component.
(d) High efficiency heating and cooling equipment credit. The calculated transmission heat loss coefficient
(Uo) used for meeting the requirement in § 3280.506(a) may be adjusted for heating and cooling
equipment above that required by the National Appliance Energy Conservation Act of 1987 (NAECA) by
applying the following formula:
Uo adjusted = Uo standard × [1 + (0.6) (heating efficiency increase factor) + (cooling multiplier) (cooling
efficiency increase factor)]
where:
Uo standard = Maximum Uo for Uo Zone required by § 3280.506(a)
Uo adjusted = Maximum Uo standard adjusted for high efficiency HVAC equipment
Heating efficiency increase factor = The increase factor in heating equipment efficiency measured by the
Annual Fuel Utilization Efficiency (AFUE), or the Heating Seasonal Performance Factor (HSPF) for heat pumps,
above that required by NAECA (indicated as “NAECA” in formula). The formula is heating efficiency increase
factor = AFUE (HSPF) home − AFUE (or HSPF) NAECA divided by AFUE (HSPF) NAECA.
Cooling efficiency increase factor = the increase factor in the cooling equipment efficiency measured by the
Seasonal Energy Efficiency Ratio (SEER) above that required by NAECA.
The formula being cooling equipment = SEER home - SEER NAECA divided by SEER NAECA.
The cooling multiplier for the Uo Zone is from the following table:
Uo zone

Cooling multiplier (Cm)

1

0.60 (Florida only).

1

0.20 (All other locations).

24 CFR 3280.508(d) (enhanced display)

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Uo zone

24 CFR 3280.508(e)

Cooling multiplier (Cm)

2

0.07.

3

0.03.

(e) U values for any glazing (e.g., windows, skylights, and the glazed portions of any door) must be based on
tests using AAMA 1503.1-1988, Voluntary Test Method for Thermal Transmittance and Condensation
Resistance of Windows, Doors, and Glazed Wall Sections, or the National Fenestration Rating Council 100,
1997 Edition, Procedure for Determining Fenestration Product U-factors. In the absence of tests,
manufacturers are to use the residential window U values contained in Chapter 29, Table 5 of the 1997
ASHRAE Handbook of Fundamentals, Inch-Pound Edition. In the event that the classification of the
window type is indeterminate, the manufacturer must use the classification that gives the higher U value.
Where a composite of materials from two different product types is used, the product is to be assigned
the higher U value. For the purpose of calculating Uo values, storm windows are treated as an additional
pane.
(f) Annual energy used based compliance. As an alternative, homes may demonstrate compliance with the
annual energy used implicit in the coefficient of heat transmission (Uo) requirement. The annual energy
use determination must be based on generally accepted engineering practices. The general requirement
is to demonstrate that the home seeking compliance approval has a projected annual energy use,
including both heating and cooling, less than or equal to a similar “base case” home that meets the
standard. The energy use for both homes must be calculated based on the same assumptions; including
assuming the same dimensions for all boundaries between conditioned and unconditioned spaces, site
characteristics, usage patterns and climate.
[58 FR 55011, Oct. 25, 1993, as amended at 70 FR 72047, Nov. 30, 2005]

§ 3280.509 Criteria in absence of specific data.
In the absence of specific data, for purposes of heat-loss/gain calculation, the following criteria shall be used:
(a) Infiltration heat loss. In the absence of measured infiltration heat loss data, the following formula shall be
used to calculate heat loss due to infiltration and intermittently operated fans exhausting to the outdoors.
The perimeter calculation shall be based on the dimensions of the pressure envelope.
Infiltration Heat-Loss = 0.7 (T) (ft. of perimeter), BTU/hr.
where: T = 70 minus the heating system capacity certification temperature stipulated in the Heating Certificate,
in F.
(b) Framing areas.
Wall

15 percent of wall area less windows and doors.

Floor and Ceiling

10 percent of the area.

(c) Insulation compression. Insulation compressed to less than nominal thickness and loose-fill insulation in
sloping cavities must have its nominal R-values reduced in compressed areas in accordance with the
following table:

24 CFR 3280.509(c) (enhanced display)

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24 CFR 3280.509(c)

Table to Paragraph (c) - Effect of Insulation Compression and Restriction on
R-Values
Original thickness
(%)

Non-uniform (a) restriction
Batt
(%)

Uniform (b)
compression batt
(%)

Blown
(%)

0

20

15

0

1

26

21

1

2

32

25

2

3

36

28

4

4

38

30

5

5

41

32

7

6

43

33

8

7

45

35

10

8

46

36

11

9

48

38

13

10

49

39

14

11

51

40

15

12

52

42

17

13

53

43

18

14

54

44

20

15

55

45

21

16

57

46

22

17

58

47

24

18

59

48

25

19

59

49

26

20

60

50

28

21

61

51

29

22

62

52

30

23

63

52

31

24

64

53

33

25

65

54

34

26

65

55

35

27

66

56

36

28

67

57

37

29

68

57

39

30

68

58

40

31

69

59

41

32

70

60

42

33

70

60

43

34

71

61

44

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Original thickness
(%)

24 CFR 3280.509(c)

Non-uniform (a) restriction
Batt
(%)

Uniform (b)
compression batt
(%)

Blown
(%)

35

72

62

45

36

72

63

47

37

73

63

48

38

74

64

49

39

74

65

50

40

75

65

51

41

75

66

52

42

76

67

53

43

76

68

54

44

77

68

55

45

78

69

56

46

78

70

57

47

79

70

58

48

79

71

59

49

80

71

60

50

80

72

61

51

81

73

62

52

81

73

63

53

82

74

64

54

82

75

65

55

83

75

65

56

83

76

66

57

84

76

67

58

84

77

68

59

84

78

69

60

85

78

70

61

85

79

71

62

86

79

72

63

86

80

73

64

87

81

74

65

87

81

74

66

88

82

75

67

88

82

76

68

88

83

77

69

89

84

78

70

89

84

78

71

90

85

79

72

90

85

80

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Original thickness
(%)

24 CFR 3280.509(c)

Non-uniform (a) restriction
Batt
(%)

Uniform (b)
compression batt
(%)

Blown
(%)

73

90

86

81

74

91

86

82

75

91

87

82

76

92

87

83

77

92

88

84

78

92

89

85

79

93

89

85

80

93

90

86

81

93

90

87

82

94

91

88

83

94

91

88

84

95

92

89

85

95

92

90

86

95

93

91

87

96

93

91

88

96

94

92

89

96

94

93

90

97

95

93

91

97

95

94

92

97

96

95

93

98

96

95

94

98

97

96

95

98

97

97

96

99

98

97

97

99

98

98

98

99

99

99

99

100

99

99

100

100

100

100

Note: To use this table, first compute the restricted insulation thickness as a fraction of the
uncompressed (full) insulation thickness. Then look up the R-value remaining from the appropriate
column (Non-uniform Restriction, Batt Non-uniform Restriction, Blown or Uniform Compression,
Batt). Example: Assume a section of loose-fill ceiling insulation went from R-25 insulation at a
height of 10 inches to a minimum height of 2 inches at the edge of the ceiling. The ratio of
minimum to full thickness is 0.20 (2 divided by 10). Look up 0.20 (20 percent), read across to
column 3 (Non-uniform Restriction, Blown), and read 50 percent. Therefore, the R-value of the
loose-fill insulation over the restricted area would be R-12.5 (50 percent of 25).
(a) Non-uniform restriction is that which occurs between non-parallel planes, such as in the ceiling
near the eaves.
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24 CFR 3280.509(d)

(b) Uniform compression is compression between parallel planes, such as that which occurs in a
wall.
(d) Air supply ducts within floor cavity. Air supply ducts located within a floor cavity shall be assumed to be
heating or cooling the floor cavity to living space temperatures unless the duct is structurally isolated by
the framing system or thermally insulated from the rest of the floor cavity with a thermal insulation at
least equal to R-4.
(e) Air supply ducts within ceiling cavity. Where supply ducts are located in ceiling cavities, the influence of
the duct on cavity temperatures shall be considered in calculating envelope heat loss or heat gain.
(f) The supply duct loss (and/or heat gain where applicable - See § 3280.511) shall be calculated using the
actual duct surface area and the actual thickness of insulation between the duct and outside of the
manufactured home. If there is an air space of at least 1⁄2 inch between the duct and the insulation, heat
loss/gain need not be calculated if the cavity in which the duct is located is assumed to be at living space
temperature. The average temperature inside the supply duct, including ducts installed outside the
manufactured home, shall be assumed to be 130 F for purposes of calculation of heat loss and 60 F for
heat gain.
(g) Return air cavities. Cavities used as return air plenums shall be considered to be at living space
temperature.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 78 FR 73984, Dec. 9, 2013]

§ 3280.510 Heat loss certificate.
The manufactured home manufacturer shall permanently affix the following “Certificate” to an interior surface of the
home that is readily visible to the homeowner. The “Certificate” shall specify the following:
(a) Heating zone certification. The design zone at which the manufactured home heat loss complies with §
3280.506(a).
(b) Outdoor certification temperature. The lowest outdoor temperature at which the installed heating
equipment will maintain a 70 °F temperature inside the home without storm sash or insulating glass for
Zones 1 and 2, and with storm sash or insulating glass for Zone 3 and complying with § 3280.508 and §
3280.509.
(c) Operating economy certification temperature. The temperature to be specified for operating economy and
energy conservation shall be 20 °F or 30% of the design temperature difference, whichever is greater,
added to the temperature specified as the heating system capacity certification temperature without
storm windows or insulating glass in Zones 1 and 2 and with storm windows or insulating glass in Zone 3.
Design temperature difference is 70° minus the heating system capacity certification temperature in
degrees Fahrenheit.

HEATING CERTIFICATE
Home Manufacturer
Plant Location

24 CFR 3280.510(c) (enhanced display)

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24 CFR 3280.510(d)

Home Model

(INCLUDE UO VALUE ZONE MAP)
This manufactured home has been thermally insulated to conform with the requirements of the Federal
Manufactured Home Construction and Safety Standards for all locations within Uo Value Zone ____.
Heating Equipment Manufacturer
Heating Equipment Model
The above heating equipment has the capacity to maintain an average 70F temperature in this home at outdoor
temperatures of [see paragraph (b) of this section] F. To maximize furnace operating economy and to conserve
energy, it is recommended that this home be installed where the outdoor winter design temperature (97 1/2%)
is not higher than [see paragraph (c) of this section] F degrees Fahrenheit.
The above information has been calculated assuming a maximum wind velocity of 15 MPH at standard
atmospheric pressure.
(d) The following additional statement must be provided on the heating certificate and data plate required by
§ 3280.5 when the home is built with a vapor retarder of not greater than one perm (dry cup method) on
the exterior side of the insulation: “This home is designed and constructed to be sited only in humid or
fringe climate regions as shown on the Humid and Fringe Climate Map.” A reproduction of the Humid and
Fringe Climate Map in § 3280.504 is to be provided on the heating certificate and data plate. The map
must be not less than 31⁄2 inch × 21⁄4 inch in size and may be combined with the Uo Value Zone Map for
Manufactured Housing in § 3280.506.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55011, Oct. 25, 1993; 70 FR 72048,
Nov. 30, 2005]

§ 3280.511 Comfort cooling certificate and information.
(a) The manufactured home manufacturer shall permanently affix a “Comfort Cooling Certificate” to an
interior surface of the home that is readily visible to the home owner. This certificate may be combined
with the heating certificate required in § 3280.510. The manufacturer shall comply with one of the
following three alternatives in providing the certificate and additional information concerning the cooling
of the manufactured home:
(1) Alternative I. If a central air conditioning system is provided by the home manufacturer, the heat gain
calculation necessary to properly size the air conditioning equipment shall be in accordance with
procedures outlined in chapter 22 of the 1989 ASHRAE Handbook of Fundamentals, with an
assumed location and orientation. The following shall be supplied in the Comfort Cooling Certificate:
Air Conditioner Manufacturer
Air Conditioner Model

24 CFR 3280.511(a)(1) (enhanced display)

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24 CFR 3280.511(a)(2)

Certified Capacity ______ BTU/Hr. in accordance with the appropriate Air Conditioning and Refrigeration
Institute Standards
The central air conditioning system provided with this home has been sized, assuming an orientation of
the front (hitch) end of the home facing ______ and is designed on the basis of a 75 °F indoor temperature
and an outdoor temperature of __ °F dry bulb and __ °F wet bulb.

Example Alternate I
COMFORT COOLING CERTIFICATE
Manufactured Home Mfg
Plant Location
Manufactured Home Model
Air Conditioner Manufacturer
Certified Capacity ______ BTU/Hr. in accordance with the appropriate Air Conditioning and Refrigeration
Institute Standards.
The central air conditioning system provided with this home has been sized assuming an orientation of
the front (hitch end) of the home facing ______. On this basis, the system is designed to maintain an
indoor temperature of 75 °F when outdoor temperatures are __ °F dry bulb and __ °F wet bulb.
The temperature to which this home can be cooled will change depending upon the amount of exposure
of the windows to the sun's radiant heat. Therefore, the home's heat gains will vary dependent upon its
orientation to the sun and any permanent shading provided. Information concerning the calculation of
cooling loads at various locations, window exposures and shadings are provided in chapter 22 of the 1989
edition of the ASHRAE Handbook of Fundamentals.
(2) Alternative 2. For each home suitable for a central air cooling system, the manufacturer shall provide
the following statement: “This air distribution system of this home is suitable for the installation of a
central air conditioning system.”

Example Alternate 2
COMFORT COOLING CERTIFICATE
Manufactured Home Manufacturer
Plant Location
Manufactured Home Model

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24 CFR 3280.511(a)(3)

This air distribution system of this home is suitable for the installation of central air conditioning.
The supply air distribution system installed in this home is sized for Manufactured Home Central Air
Conditioning System of up to ______ B.T.U./Hr. rated capacity which are certified in accordance with the
appropriate Air Conditioning and Refrigeration Institute Standards. When the air circulators of such air
conditioners are rated at 0.3 inch water column static pressure or greater for the cooling air delivered to
the manufactured home supply air duct system.
Information necessary to calculate cooling loads at various locations and orientations is provided in the
special comfort cooling information provided with this manufactured home.
(3) Alternative 3. If the manufactured home is not equipped with an air supply duct system, or if the
manufacturer elects not to designate the home as being suitable for the installation of a central air
conditioning system, the manufacturer shall provide the following statement: “This air distribution
system of this home has not been designed in anticipation of its use with a central air conditioning
system.”

Example Alternate 3
COMFORT COOLING CERTIFICATE
Manufactured Home Mfg
Plant Location
Manufactured Home Model
The air distribution system of this home has not been designed in anticipation of its use with a central air
conditioning system.
(b) For each home designated as suitable for central air conditioning the manufacturer shall provide the
maximum central manufactured home air conditioning capacity certified in accordance with the ARI
Standard 210/240-89 Unitary Air-Conditioning and Air-Source Heat Pump Equipment and in accordance
with § 3280.715(a)(3). If the capacity information provided is based on entrances to the air supply duct at
other than the furnace plenum, the manufacturer shall indicate the correct supply air entrance and return
air exit locations.
(c) Comfort cooling information. For each manufactured home designated, either “suitable for” or “provided
with” a central air conditioning system, the manufacturer shall provide comfort cooling information
specific to the manufactured home necessary to complete the cooling load calculations. The comfort
cooling information shall include a statement to read as follows:
To determine the required capacity of equipment to cool a home efficiently and economically, a cooling load
(heat gain) calculation is required. The cooling load is dependent on the orientation, location and the structure
of the home. Central air conditioners operate most efficiently and provide the greatest comfort when their
capacity closely approximates the calculated cooling load. Each home's air conditioner should be sized in
accordance with chapter 22 of the American Society of Heating, Refrigerating and Air Conditioning Engineers
(ASHRAE) Handbook of Fundamentals, 1989 Edition, once the location and orientation are known.
24 CFR 3280.511(c) (enhanced display)

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24 CFR 3280.601

Information Provided by the Manufacturer Necessary To Calculate
Sensible Heat Gain
Walls (without windows and doors)

U

Ceilings and roofs of light color

U

Ceilings and roofs of dark color

U

Floors

U

Air ducts in floor

U

Air ducts in ceiling

U

Air ducts installed outside the home

U

Information necessary to calculate duct areas.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55012, Oct. 25, 1993]

Subpart G - Plumbing Systems
§ 3280.601 Scope.
Subpart G of this standard covers the plumbing materials, fixtures, and equipment installed within or on
manufactured homes. It is the intent of this subpart to assure water supply, drain, waste and vent systems which
permit satisfactory functioning and provide for health and safety under all conditions of normal use.

§ 3280.602 Definitions.
The following definitions are applicable to subpart G only:
Accessible, when applied to a fixture, connection, appliance or equipment, means having access thereto, but
which may require removal of an access panel or opening of a door.
Air gap (water distribution system) means the unobstructed vertical distance through the free atmosphere
between the lowest opening from any pipe or faucet supplying water to a tank, plumbing fixture, water
supplied appliances, or other device and the flood level rim of the receptacle.
Backflow means the flow of water or other liquids, mixtures, or substances into the distributing pipes of a
potable supply of water from any source or sources other than its intended sources.
Backflow connection means any arrangement whereby backflow can occur.
Backflow preventer means a device or means to prevent backflow.
Branch means any part of the piping system other than a riser, main or stack.
Common vent means a vent connecting at the junction of fixture drains and serving as a vent for more than one
fixture.
Continuous vent means a vertical vent that is a continuation of the drain to which it connects.
Continuous waste means a drain from two or more fixtures connected to a single trap.

24 CFR 3280.602 “Continuous waste” (enhanced display)

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24 CFR 3280.602 “Critical level”

Critical level means a point established by the testing laboratory (usually stamped on the device by the
manufacturer) which determines the minimum elevation above the flood level rim of the fixture or
receptacle served on which the device may be installed. When a backflow prevention device does not bear
a critical level marking, the bottom of the vacuum breaker, combination valve, or of any such approved or
listed device shall constitute the critical level.
Cross connection means any physical connection or arrangement between two otherwise separate systems or
sources, one of which contains potable water and the other either water, steam, gas or chemical of
unknown or questionable safety whereby there may be a flow from one system or source to the other, the
direction of flow depending on the pressure differential between the two systems.
Developed length means that length of pipe measured along the center line of the pipe and fittings.
Diameter, unless otherwise specifically stated, means the nominal (inside) diameter designated commercially.
Drain means a pipe that carries waste, water, or water-borne waste in a drainage system.
Drain connector means the removable extension, consisting of all pipes, fittings and appurtenances, from the
drain outlet to the drain inlet serving the manufactured home.
Drain outlet means the lowest end of the main or secondary drain to which a sewer connection is made.
Drainage system means all piping within or attached to the structure that conveys sewage or other liquid waste
to the drain outlet, not including the drain connector.
Fixture drain means the drain from the trap of a fixture to the junction of that drain with any other drain pipe.
Fixture supply means the water supply pipe connecting a fixture to a branch water supply pipe or directly to a
main water supply pipe.
Flood-level means the level in the receptacle over which water would overflow to the outside of the receptacle.
Flooded means the condition which results when the liquid in a container or receptacle rises to the flood-level.
Flush tank means that portion of a water closet that is designed to contain sufficient water to adequately flush
the fixture.
Flush valve means a device located at the bottom of a flush tank for flushing a water closet.
Flushometer tank: means a device integrated within an air accumulator vessel which is designed to discharge a
predetermined quantity of water to fixtures for flushing purposes.
Flushometer valve means a device which discharges a predetermined quantity of water to a fixture for flushing
purposes and is closed by direct water pressure.
Grade means the fall (slope) of a pipe in reference to a horizontal plane expressed in inches per foot length.
Horizontal branch means any pipe extending laterally, which receives the discharge from one or more fixture
drains and connects to the main drain.
Horizontal pipe means any pipe or fitting which makes an angle of not more than 45 degrees with the horizontal.
Indirect waste receptor means a receptor that receives a discharge waste pipe that is not directly connected to a
receptor but maintains a suitable air gap between the end of the pipe and the top of the drain.
Individual vent means a pipe installed to vent a fixture drain.

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24 CFR 3280.602 “Inlet coupling”

Inlet coupling means the terminal end of the water system to which the water service connection is attached. It
may be a swivel fitting or threaded pipe end.
Main means the principal artery of the system to which branches may be connected.
Main drain means the lowest pipe of a drainage system which receives sewage from all the fixtures within a
manufactured home and conducts these wastes to the drain outlet.
Main vent means the principal artery of the venting system to which vent branches may be connected.
Mechanical trap vent device means a device that automatically opens to admit air to a fixture drain above the
connection of the trap arm so as to prevent siphonage, and closes tightly when the pressure within the
drainage system is equal to or greater than atmospheric pressure, so as to prevent the escape of gases
from the drainage system into the manufactured home.
Offset means a combination of pipe and/or fittings that brings one section of the pipe out of line but into a line
parallel with the other section.
Pitch. See Grade.
Plumbing appliance: means any one of a special class of plumbing fixture which is intended to perform a special
plumbing function. Its operation and/or control may be dependent upon one or more energized
components, such as motors, control, heating elements, or pressure or temperature-sensing elements.
Such fixture may operate automatically through one or more of the following actions: A time cycle, a
temperature range, a pressure range, a measured volume or weight, or the fixture may be manually
adjusted or controlled by the user or operator.
Plumbing appurtenance: means a manufactured device, or a prefabricated assembly, or an on-the-job assembly
of component parts, and which is an adjunct to the basic piping system and plumbing system and
plumbing fixtures. An appurtenance demands no additional water supply, nor does it add any discharge
load to a fixture or the drainage system.
Plumbing fixtures means receptacles, devices, or appliances which are supplied with water or which receive
liquid or liquid-borne wastes for discharge into the drainage system.
Plumbing system means the water supply and distribution pipes; plumbing fixtures, faucets and traps; soil,
waste and vent pipes; and water-treating or water-using equipment.
Primary vent. See main vent.
Relief vent means an auxiliary vent which permits additional circulation of air in or between drainage and vent
systems.
Secondary vent means any vent other than the main vent or those serving each toilet.
Sewage means any liquid waste containing animal or vegetable matter in suspension or solution, and may
include liquids containing chemicals in solution.
Siphonage means the loss of water seal from fixture traps resulting from partial vacuum in the drainage system
which may be of either of the following two types, or a combination of the two:
(a) Self-siphonage resulting from vacuum in a fixture drain generated solely by the discharge of the
fixture served by that drain, or,
(b) Induced siphonage resulting from vacuum in the drainage system generated by the discharge of one
or more fixtures other than the one under observation.
24 CFR 3280.602 “Siphonage” (b) (enhanced display)

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24 CFR 3280.602 “Trap”

Trap means a fitting or device designed and constructed to provide a liquid seal that will prevent the back
passage of air without materially affecting the flow of liquid waste through it.
Trap arm means the portion of a fixture drain between a trap and its vent.
Trap seal means the vertical depth of liquid that a trap will retain.
Vacuum breaker. See backflow preventer.
Vent cap means the device or fitting which protects the vent pipe from foreign substance with an opening to the
atmosphere equal to the area of the vent it serves.
Vent system means that part of a piping installation which provides circulation of air within a drainage system.
Vertical pipe means any pipe or fitting which makes an angle of not more than 45 degrees with the vertical.
Water closet drain means that part of the drainage piping which receives the discharge from each individual
water closet.
Water connection means the fitting or point of connection for the manufactured home water distribution system
designed for connection to a water supply.
Water connector means the removable extension connecting the manufactured home water distribution system
to the water supply.
Water distribution system means potable water piping within or permanently attached to the manufactured
home.
Wet vent means a vent which also serves as a drain for one or more fixtures.
Wet vented drainage system means the specially designed system of drain piping that also vents one or more
plumbing fixtures by means of a common waste and vent pipe.
Whirlpool bathtub means a plumbing appliance consisting of a bathtub fixture which is equipped and fitted with
a circulation piping system, pump, and other appurtenances and is so designed to accept, circulate, and
discharge bathtub water upon each use.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4584, Feb. 12, 1987; 52 FR 47553,
Dec. 15, 1987; 58 FR 55012, Oct. 25, 1993; 78 FR 73984, Dec. 9, 2013' 86 FR 2521, Jan. 12, 2021]

§ 3280.603 General requirements.
(a) Minimum requirements. Any plumbing system installed in a manufactured home shall conform, at least,
with the provisions of this subpart.
(1) General. The plumbing system shall be of durable material, free from defective workmanship, and so
designed and constructed as to give satisfactory service for a reasonable life expectancy.
(2) Conservation. Each water closet must not use more than 1.6 gallons of water per flush.
(3) Connection to drainage system. All plumbing, fixtures, drains, appurtenances, and appliances
designed or used to receive or discharge liquid waste or sewage shall be connected to the
manufactured home drainage system in a manner provided by this standard.

24 CFR 3280.603(a)(3) (enhanced display)

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24 CFR 3280.603(a)(4)

(4) Workmanship. All design, construction, and workmanship shall be in conformance with accepted
engineering practices and shall be of such character as to secure the results sought to be obtained
by this standard.
(5) Components. Plumbing materials, devices, fixtures, fittings, equipment, appliances, appurtenance,
and accessories intended for use in or attached to a manufactured home shall conform to one of the
applicable standards referenced in § 3280.604. Where an applicable standard is not referenced, or
an alternative recognized standard is utilized, the plumbing component shall be listed by a nationally
recognized testing laboratory, inspection agency or other qualified organization as suitable for the
intended use.
(6) Prohibited fittings and practices.
(i)

Drainage or vent piping shall not be drilled and tapped for the purpose of making connections.

(ii) Except as specifically provided elsewhere in this standard, vent pipes shall not be used as
waste or drain pipes.
(iii) Fittings, connections, devices, or methods of installation that obstruct or retard the flow of
sewage, or air in the drainage or venting systems in an amount greater than the normal
frictional resistance to flow shall not be used unless their use is acceptable in this standard or
their use is accepted as having a desirable and acceptable function of ultimate benefit to the
proper and continued functioning of the plumbing system.
(iv) Cracks, holes, or other imperfections in materials shall not be concealed by welding, brazing, or
soldering or by paint, wax, tar, or other leak-sealing or repairing agents.
(v) Piping, fixtures or equipment shall be located so as not to interfere with the normal use or with
the normal operation and use of windows, doors or other required facilities.
(vi) Galvanized pipe shall not be bent or welded.
(7) Alignment of fittings. All valves, pipes, and fittings shall be installed in correct relationship to the
direction of flow.
(b) Protective requirements.
(1) Cutting structural members. Structural members shall not be unnecessarily or carelessly weakened
by cutting or notching.
(2) Exposed piping. All piping, pipe threads, hangers, and support exposed to the weather, water, mud,
and road hazard, and subject to damage therefrom, shall be painted, coated, wrapped, or otherwise
protected from deterioration.
(3) Road damage. Pipes, supports, drains, outlets, or drain hoses shall not extend or protrude in a
manner where they could be unduly subjected to damage during transit.
(4) Freezing. All piping and fixtures subject to freezing temperatures shall be insulated or protected to
prevent freezing, under normal occupancy. The manufacturer shall provide:
(i)

Written installation instructions for the method(s) required for compliance to this section;

(ii) A statement in the installation instructions required by § 3280.306(b), stating that if the heat
tape or pipe heating cable is used, it must be listed for use with manufactured homes.
(iii) A receptacle outlet complying with § 3280.806(d)(10).
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24 CFR 3280.603(b)(5)

(5) All piping, except the fixture trap, shall be designed to allow drainage.
(6) Rodent resistance. All exterior openings around piping and equipment shall be sealed to resist the
entrance of rodents.
(7) Piping and electrical wiring shall not pass through the same holes in walls, floors or roofs. Plastic
piping shall not be exposed to heat in excess of manufacturers recommendation or radiation from
heat producing appliances.
[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 54383, Oct. 5, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended
at 58 FR 55012, Oct. 25, 1993; 78 FR 73985, Dec. 9, 2013]

§ 3280.604 Materials.
(a) Minimum standards. Materials, devices, fixtures, fittings, equipment, appliances, appurtenances and
accessories shall conform to one of the standards in the following table and be free from defects. Where
an appropriate standard is not indicated in the table or a standard not indicated in the table is preferred,
the item may be used if it is listed. A listing is also required when so specified in other sections of this
subpart.
(b) Where more than one standard is referenced for a particular material or component, compliance with only
one of those standards is acceptable. Exceptions:
(1) When one of the reference standards requires evaluation of chemical, toxicity or odor properties
which are not included in the other standard, then conformance to the applicable requirements of
each standard shall be demonstrated;
(2) When a plastic material or component is not covered by the Standards in the following table, it must
be certified as non-toxic in accordance with ANSI/NSF 61-2001, Drinking water system components Health effects.

Ferrous Pipe and Fittings
Gray Iron Threaded Fittings - ANSI/ASME B16.4-1992.
Malleable Iron Threaded Fittings - ANSI/ASME B16.3-1992.
Material and Property Standard for Special Cast Iron Fittings - IAPMO PS 5-84.
Welding and Seamless Wrought Steel Pipe - ANSI/ASME B36.10-1979.
Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless - ASTM
A53-93.
Pipe Threads, General Purpose (Inch) - ANSI/ASME B1.20.1-1983.
Standard Specification for Cast Iron Soil Pipe and Fittings - ASTM A74-92.
Standard Specification for Hubless Cast Iron Soil Pipe and Fittings for Sanitary and Storm Drain, Waste, and
Vent Piping Applications - CISPI-301-90.
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Nonferrous Pipe and Fittings
Standard Specification for Seamless Copper Pipe, Standard Sizes - ASTM B42-93.
Standard Specification for General Requirements for Wrought Seamless Copper and Copper-Alloy Tube - ASTM
B251-93.
Standard Specification for Seamless Copper Water Tube - ASTM B88-93.
Standard Specification for Copper Drainage Tube (DWV) - ASTM B306-92.
Wrought Copper and Copper Alloy Solder-Joint Pressure Fitting - ASME/ANSI B16.22-1989.
Wrought Copper and Wrought Copper Alloy Solder-Joint Drainage Fittings-DWV - ASME/ANSI B16.29-1986.
Cast Copper Alloy Solder-Joint Pressure Fittings - ANSI B16.18-1984.
Cast Copper Alloy Solder-Joint Drainage Fittings-DWV - ASME B16.23-1992.
Cast Copper Alloy Fittings for Flared Copper Tubes - ASME/ANSI B16.26-1988.
Standard Specification for Seamless Red Brass Pipe, Standard Sizes - ASTM B43-91.
Cast Bronze Threaded Fittings, Classes 125 and 250 - ANSI/ASME B16.15-1985.

Plastic Pipe and Fittings
Standard Specification Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40 Plastic Drain, Waste, and Vent Pipe
and Fittings - ASTM D2661-91.
Standard Specification for Poly (Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and Fittings - ASTM
D2665-91b.
Standard Specification for Drain, Waste, and Vent (DWV) Plastic Fittings Patterns - ASTM D3311-92.
Standard Specification for Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40, Plastic Drain, Waste, and Vent
Pipe With a Cellular Core - ASTM F628-91.
Standard Specification for Chlorinated Poly (Vinyl Chloride) (CPVC) Plastic Hot- and Cold-Water Distribution
Systems - ASTM D2846-92.
Standard Specification for Polybutylene (PB) Plastic Hot- and Cold-Water Distribution Systems - ASTM
D3309-92a.
Plastic Piping Components and Related Materials - ANSI/NSF 14-1990.

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Standard Specification for Crosslinked Polyethylene (PEX) Tubing - ASTM F876-10 (incorporated by reference,
see § 3280.4).
Standard Specification for Crosslinked Polyethylene (PEX) Plastic Hot- and Cold-Water Distribution Systems ASTM F877-07 (incorporated by reference, see § 3280.4).

Miscellaneous
Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings, ASTM C564-97 (incorporated by
reference, see § 3280.4).
Backflow Valves - ANSI A112.14.1-1975.
Plumbing Fixture Setting Compound - TTP 1536A-1975.
Material and Property Standard for Cast Brass and Tubing P-Traps - IAPMO PS 2-89.
Relief Valves for Hot Water Supply Systems, ANSI Z21.22-1999 (incorporated by reference, see § 3280.4).
Standard Specification for Solvent Cement for Acrylonitrile-Butadiene-Styrene (ABS) Plastic Pipe and Fittings ASTM D2235-88.
Standard Specification for Solvent Cements for Poly (Vinyl Chloride) (PVC) Plastic Piping Systems - ASTM
D2564-91a.
Specification for Neoprene Rubber Gaskets for HUB and Spigot Cast Iron Soil Pipe and Fittings - CISPI-HSN-85.
Plumbing System Components for Manufactured Homes and Recreational Vehicles - ANSI/NSF 24-1988.
Material and Property Standard for Diversion Tees and Twin Waste Elbow - IAPMO PS 9-84.
Material and Property Standard for Flexible Metallic Water Connectors - IAPMO PS 14-89.
Material and Property Standard for Dishwasher Drain Airgaps - IAPMO PS 23-89.
Material and Property Standards for Backflow Prevention Assemblies - IAPMO PS 31-91.
Performance Requirements for Air Admittance Valves for Plumbing Drainage Systems, Fixture and Branch
Devices - ASSE Standard #1051, 1990 Revised: 1996/ANSI 1998.
Drinking Water System Components-Health Effects - ANSI/NSF 61-2001.

Plumbing Fixtures
Plumbing Fixtures (General Specifications) - FS WW-P-541E/GEN-1980.
Vitreous China Plumbing Fixtures - ANSI/ASME A112.19.2(M)-1990.
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Enameled Cast Iron Plumbing Fixtures - ANSI/ASME A112.19.1M-1987.
Porcelain Enameled Formed Steel Plumbing Fixtures - ANSI/ASME A112.19.4(M)-1984.
Plastic Bathtub Units with Addenda Z124.1a-1990 and Z124.16-1991 - ANSI Z124.1-1987.
Standard for Porcelain Enameled Formed Steel Plumbing Fixtures - IAPMO TSC 22-85.
Plastic Shower Receptors and Shower Stalls with Addendum Z124.2a-1990 - ANSI Z124.2-1987.
Stainless Steel Plumbing Fixtures (Designed for Residential Use) - ANSI/ASME A112.19.3M-1987.
Material and Property Standard for Drains for Prefabricated and Precast Showers - IAPMO PS 4-90.
Plastic Lavatories with Addendum Z124.3a-1990 - ANSI Z124.3-1986.
Standard for Safety Glazing Materials used in Buildings - Safety Performance Specifications and Methods of
Test, ANSI Z97.1-2004 (incorporated by reference, see § 3280.4).
Water Heater Relief Valve Drain Tubes - ASME A112.4.1-1993.
Flexible Water Connectors - ASME A112.18.6-1999.
Performance Requirements for Backflow Protection Devices and Systems in Plumbing Fixture Fittings - ASME
A112.18.3M-1996.
Non-Vitreous Ceramic Plumbing Fixtures - ASME A112.19.9M-1991.
Dual Flush Devices for Water Closets - ASME A119.19.10-1994.
Deck Mounted Bath/Shower Transfer Valves with Integral Backflow Protection - ASME A112.18.7-1999.
Plastic Fittings for Connecting Water Closets to the Sanitary Drainage System - ASME A112.4.3-1999.
Hydraulic Performance Requirements for Water Closets and Urinals, ASME A112.19.6-1995.
Plumbing Fixture Fittings - ASME/ANSI A112.18.1M-1989.
Trim for Water Closet, Bowls, Tanks, and Urinals - ANSI A112.19.5-1979.
Plastic Water Closets, Bowls, and Tanks with Addenda Z124.4a-1990 - ANSI Z124.4-1986.
ANSI Z124.5, Plastic Toilet (Water Closets) Seats, 1997.
ANSI Z124.7, Prefabricated Plastic Spa Shells, 1997.

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Whirlpool Bathtub Appliances - ASME/ANSI A112.19.7M-1987.
ANSI Z-124.9, Plastic Urinal Fixtures, 1994.
Performance Requirements for Individual Thermostatic Pressure Balancing and Combination Control for
Bathing Facilities - ASSE 1016-1988 (ANSI 1990).
Performance Requirements for Pressurized Flushing Devices (Flushometers) for Plumbing Fixtures - ASSE
1037-1990 (ANSI-1990).
Performance Requirements for Water Closet Flush Tank Fill Valves (Ballcocks) - ASSE 1002 Revision 5-1986
(ANSI/ASSE-1979).
Performance Requirements for Hand-held Showers - ASSE 1014-1989 (ANSI-1990).
Hydrants for Utility and Maintenance Use - ANSI/ASME A112.21.3M-1985.
Performance Requirements for Home Laundry Equipment - ASSE 1007-1986.
Performance Requirements for Hot Water Dispensers, Household Storage Type Electrical - ASSE 1023, (ANSI/
ASSE-1979).
Plumbing Requirements for Residential Use (Household) Dishwashers - ASSE 1006, (ASSE/ANSI-1986).
Performance Requirements for Household Food Waste Disposer Units - ASSE 1008-1986.
Performance Requirements for Temperature Activated Mixing Valves for Primary Domestic Use - ASSE
1017-1986.
Water Hammer Arresters - ANSI A112.26.1-1969 (R 1975).
Suction Fittings for Use in Swimming Pools, Wading Pools, Spas, Hot Tubs, and Whirlpool Bathtub Appliances ASME/ANSI A112.19.8M-1989.
Air Gaps in Plumbing Systems - ASME A112.1.2-1991.
Performance Requirements for Diverters for Plumbing Faucets with Hose Spray, Anti-Siphon Type, Residential
Applications - ASSE 1025 (ANSI/ASSE-1978).
Performance Requirements for Pipe Applied Atmospheric Type Vacuum Breakers - ASSE 1001 (ASSE/
ANSI-1990).
Performance Requirements for Hose Connection Vacuum Breakers - ASSE 1011-1981 (ANSI-1982).
Performance Requirements for Wall Hydrants, Frost Proof Automatic Draining, Anti-Backflow Types - ANSI/
ASSE 1019-1978.
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24 CFR 3280.605

Performance Requirements for Automatic Compensating Values for Individual Shower and Tub/Shower
Combinations, approved January 2005 ASSE 1016-2005 (incorporated by reference, see § 3280.4).
Performance Requirements for Water Temperature Limiting Devices, approved February 2004, ASSE 1070-2004
(incorporated by reference, see § 3280.4).
[58 FR 55013, Oct. 25, 1993, as amended at 70 FR 72048, Nov. 30, 2005; 78 FR 73985, Dec. 9, 2013; 79 FR 31863, June 3, 2014]

§ 3280.605 Joints and connections.
(a) Tightness. Joints and connections in the plumbing system shall be gastight and watertight for the
pressures required under testing procedures.
(b) Assembling of pipe. All joints and connections shall be correctly assembled for tightness. Pipe threads
shall be fully engaged with the threads of the fitting. Plastic pipe and copper tubing shall be inserted to
the full depth of the solder cup or welding sockets of each fitting. Pipe threads and slip joints shall not be
wrapped with string, paper, putty, or similar fillers.
(c) Threaded joints. Threads for screw pipe and fittings shall conform to the approved or listed standard. Pipe
ends shall be reamed out to size of bore. All burrs, chips, cutting oil and foreign matter shall be removed.
Pipe joint cement or thread lubricant shall be of approved type and applied to male threads only.
(d) Solder joints. Solder joints for tubing shall be made with approved or listed solder type fittings. Surfaces to
be soldered shall be cleaned bright. The joints shall be properly fluxed with noncorrosive paste type flux
and, for manufactured homes to be connected to a public water system, made with solder having not
more than 0.2 percent lead.
(e) Plastic pipe, fittings and joints. Plastic pipe and fittings shall be joined by installation methods
recommended by the manufacturer or in accordance with the provisions of a recognized, approved, or
listed standard.
(f) Union joints. Metal unions in water piping shall have metal-to-metal ground seats.
(g) Flared joints. Flared joints for soft-copper water tubing shall be made with approved or listed fittings. The
tubing shall be expanded with a proper flaring tool.
(h) Cast iron soil pipe joints. Approved or listed cast iron pipe may be joined as follows:
(1) Approved or listed hub-less pipe and fittings must be permitted to be joined with listed couplings or
adapters, per the manufacturer's recommendations.
(2) Hub and plain-end soil pipe may be joined by compression fittings per the manufacturer's
recommendation.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 53 FR 23611, June 23, 1988; 78 FR
73985, Dec. 9, 2013]

§ 3280.606 Traps and cleanouts.
(a) Traps (1) Traps required. Each plumbing fixture, except listed toilets, shall be separately trapped by approved
water seal “P” traps. All traps shall be effectively vented.
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(2) Combination Fixtures. For the purposes of drainage and ventilation requirements, a two- or threecompartment sink, up to three single sinks, or up to three lavatories may be connected to one “P”
trap and considered as a single fixture, so long as the sinks and lavatories are in the same room,
have waste outlets not more than 30 inches apart, and have flood level rims at the same level. The
“P” trap must be installed at the center fixture when three such fixtures are installed.
(3) Prohibited traps. A trap which depends for its seal upon concealed interior partitions shall not be
used. Full “S” traps, bell traps, drum traps, crown-vented traps, and running traps are prohibited.
Fixtures shall not be double-trapped.
(4) Material and design. Each trap shall be self-cleaning with a smooth and uniform interior waterway.
Traps shall be manufactured of cast iron, cast brass, or drawn brass tubing of not less than No. 20
Brown and Sharpe gage, or approved or listed plastic, or other approved or listed material. Union
joints for a trap shall be beaded to provide a shoulder for the union nut. Each trap shall have the
manufacturer's name stamped or cast in the body of the trap, and each tubing trap shall show the
gage of the tubing.
(5) Trap seal. Each “P” trap shall have a water seal of not less than 2 inches and not more than 4 inches
and shall be set true to its seal.
(6) Size. Traps shall be not less than 11⁄4 inches in diameter. A trap shall not be larger than the waste
pipe to which it is connected.
(7) Location. Each trap shall be located as close to its vent and to its fixture outlet as structural
conditions will permit.
(8) Length of tailpiece. The vertical distance from a trap to the fixture outlet shall not exceed 24 inches.
(9) Installation.
(i)

Grade of trap arm. The piping between a “P” trap and the fixture tee or the vented waste line
shall be graded 1⁄4 inch per foot towards the vent and in no event shall have a slope greater
than its diameter. The vent opening at fixture tees shall not be below the weir of the “P” trap
outlet.

(ii) Trap arm offset. The piping between the “P” trap and vent may change direction or be offset
horizontally with the equivalent of no more than 180 degrees total change in direction with a
maximum of 90 degrees by any one fitting.
(iii) Concealed traps. Traps with mechanical joints shall be accessible for repair and inspection.
(iv) Removability of traps, etc. Traps shall be designed and installed so the “U” bend is removable
without removing the strainers from the fixture. Continuous waste and tail pieces which are
permanently attached to the “U” bend shall also be removable without removing the strainer
from the fixture.
(b) Cleanout openings (1) Location of cleanout fittings.
(i)

Cleanouts shall be installed if the drainage system cannot be cleaned through fixtures, drains,
or vents. Cleanouts shall also be provided when fittings of more than 45 degrees are used to
affect an offset except where long turn ells are used which provide sufficient “sweep” for
cleaning.

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(ii) A full size cleanout shall be installed at the upper end of any section of drain piping which does
not have the required minimum slope of 1⁄4 inch per foot grade.
(iii) A cleaning tool shall not be required to pass through more than 360 degrees of fittings,
excluding removable “P” traps, to reach any part of the drainage system. Water closets may be
removed for drainage system access.
(2) Access to cleanouts. Cleanouts shall be accessible through an unobstructed minimum clearance of
12 inches directly in front of the opening. Each cleanout fitting shall open in a direction opposite to
the flow or at right angles to the pipe. Concealed cleanouts that are not provided with access covers
shall be extended to a point above the floor or outside of the manufactured home, with pipe and
fittings installed, as required, for drainage piping without sags and pockets.
(3) Material. Plugs and caps shall be brass or approved or listed plastic, with screw pipe threads.
(4) Design. Cleanout plugs shall have raised heads except that plugs at floor level shall have countersunk slots.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55014, Oct. 25, 1993; 78 FR 73985,
Dec. 9, 2013]

§ 3280.607 Plumbing fixtures.
(a) General requirements (1) Quality of fixtures. Plumbing fixtures shall have smooth impervious surfaces, be free from defects
and concealed fouling surfaces, be capable of resisting road shock and vibration, and shall conform
in quality and design to listed standards. Fixtures shall be permanently marked with the
manufacturer's name or trademark.
(2) Strainers. The waste outlet of all plumbing fixtures, other than toilets, shall be equipped with a drain
fitting that will provide an adequate unobstructed waterway.
(3) Fixture Connections. Fixture tailpieces and continuous wastes in exposed or accessible locations
must be of not less than No. 20 Brown and Sharpe gauge seamless drawn-brass tubing or other
approved pipe or tubing materials. Inaccessible fixture connections must be constructed according
to the requirements for drainage piping. The diameter of each fixture tailpiece, continuous waste, or
waste and overflow must be not less than:
(i)

11⁄2 inches, for sinks of two or more compartments, dishwashers, clothes washing machines,
laundry tubs, bathtubs, and showers; and

(ii) Not less than 11⁄4 inches for lavatories or single compartment sinks having a 2-inch maximum
drain opening.
(4) Concealed connections. Concealed slip joint connections shall be provided with adequately sized
unobstructed access panels and shall be accessible for inspection and repair.
(5) Directional fitting. An approved or listed “Y” or other directional-type branch fitting shall be installed in
every tailpiece or continuous waste that receives the discharge from food waste disposal units,
dishwashing, or other force-discharge fixture or appliance. (See also § 3280.607(b)(4)(ii).)
(6) Water conservation. All lavatory faucets, showerheads, and sink faucets must not exceed a flow of
2.5 gallons per minute (gpm).
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(b) Fixtures (1) Spacing. All plumbing fixtures shall be so installed with regard to spacing as to be reasonably
accessible for their intended use.
(2) Water closets.
(i)

Water closets shall be designed and manufactured according to approved or listed standards
and shall be equipped with a water flushing device capable of adequately flushing and cleaning
the bowl at each operation of the flushing mechanism.

(ii) Water closet flushing devices shall be designed to replace the water seal in the bowl after each
operation. Flush valves, flushometer valves, flushometer tanks and ballcocks shall operate
automatically to shut off at the end of each flush or when the tank is filled to operating
capacity.
(iii) All water closets must be low consumption (1.6 gallons per flush (gpf)) closets.
(iv) Flush tanks shall be fitted with an overflow pipe large enough to prevent flooding at the
maximum flow rate of the ball cock. Overflow pipes shall discharge into the toilet, through the
tank.
(v) Floor Connection. Water closets must be securely bolted to an approved flange or other
approved fitting that is secured to the floor by means of corrosion-resistant screws. The bolts
must be of solid brass or other corrosion-resistant material and must not be less than 1⁄4 inch
in diameter. A watertight seal must be made between the water closet and flange or other
approved fitting by use of a gasket, sealing compound, or listed connector device.
(vi) Floor connection. Water closets shall be securely bolted to an approved flange or other
approved fitting which is secured to the floor by means of corrosion-resistant screws. The bolts
shall be of solid brass or other corrosion-resistant material and shall be not less than onefourth inch in diameter. A watertight seal shall be made between the water closet and flange or
other approved fitting by use of a gasket or sealing compound.
(3) Shower compartment.
(i)

Each compartment stall shall be provided with an approved watertight receptor with sides and
back extending at least 1 inch above the finished dam or threshold. In no case shall the depth
of a shower receptor be less than 2 inches or more than 9 inches measured from the top of the
finished dam or threshold to the top of the drain. The wall area shall be constructed of smooth,
noncorrosive, and nonabsorbent waterproof materials to a height not less than 6 feet above the
bathroom floor level. Such walls shall form a watertight joint with each other and with the
bathtub, receptor or shower floor. The floor of the compartment shall slope uniformly to the
drain at not less than one-fourth nor more than one-half inch per foot.

(ii) The joint around the drain connection shall be made watertight by a flange, clamping ring, or
other approved listed means.
(iii) Shower doors and tub and shower enclosures shall be constructed so as to be waterproof and,
if glazed, glazing shall comply with the Standard for Safety Glazing Materials used in Buildings Safety Performance Specifications and Methods of Test, ANSI Z97.1-2004 (incorporated by
reference, see § 3280.4).
(iv) Prefabricated plumbing fixtures shall be approved or listed.
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(v) Shower and tub-shower combination valves must be balanced pressure, thermostatic, or
combination mixing valves that conform to the requirements of ASSE 1016-2005, Performance
Requirements for Automatic Compensating Valves for Individual Shower and Tub/Shower
Combinations (incorporated by reference, see § 3280.4). Such valves must be equipped with
handle position stops that are adjustable in accordance with the valve manufacturer's
instructions and to a maximum setting of 120 °F. Hot water supplied to bathtubs and whirlpool
bathtubs are to be limited to a temperature of not greater than 120 °F by a water temperature
limiting device that conforms to the requirements of ASSE 1070-2004, Performance
Requirements for Water Temperature Limiting Devices (incorporated by reference, see §
3280.4).
(4) Dishwashing machines.
(i)

A dishwashing machine must discharge its waste through a fixed air gap installed above the
machine, through a high loop as specified by the dishwashing machine manufacturer, or into an
open standpipe receptor with a height greater than the washing compartment of the machine.
When a standpipe is used, it must be at least 18 inches, but not more than 30 inches, above the
trap weir. The drain connections from the air gap or high loop are permitted to connect to an
individual trap to a directional fitting installed in the sink tailpiece or to an opening provided on
the inlet side of a food waste disposal unit.

(ii) Drain from a dishwashing machine shall not be connected to a sink tailpiece, continuous waste
line, or trap on the discharge side of a food waste disposal unit.
(5) Clothes washing machines.
(i)

Clothes washing machines shall drain either into a properly vented trap, into a laundry tub
tailpiece with watertight connections, into an open standpipe receptor, or over the rim of a
laundry tub.

(ii) Standpipes must be either 11⁄2 inch diameter minimum nominal iron pipe size, 11⁄2 inch
diameter nominal brass tubing of not less than No. 20 Brown and Sharp gauge, or 11⁄2 inch
diameter approved plastic materials. Receptors must discharge into a vented trap or must be
connected to a laundry tub appliance by means of an approved or listed directional fitting. Each
standpipe must extend not less than 18 inches or more than 42 inches above its trap and must
terminate in an accessible location no lower than the top of the clothes washing machine. A
removable, tight-fitting cap or plug must be installed on the standpipe when the clothes washer
is not provided.
(iii) Clothes washing machine drain shall not be connected to the tailpiece, continuous waste, or
trap of any sink or dishwashing machine.
(c) Installation (1) Access. Each plumbing fixture and standpipe receptor shall be located and installed in a manner to
be accessible for usage, cleaning, repair and replacement. Access to diverter valves and other
connections from the fixture hardware is not required.
(2) Alignment. Fixtures shall be set level and in true alignment with adjacent walls. Where practical,
piping from fixtures shall extend to nearest wall.

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24 CFR 3280.607(c)(3)

(3) Brackets. Wall-hung fixtures shall be rigidly attached to walls by metal brackets or supports without
any strain being transmitted to the piping connections. Flush tanks shall be securely fastened to
toilets or to the wall with corrosive-resistant materials.
(4) Tub supports. Bathtub rims at wall shall be supported on metal hangers or on end-grain wood
blocking attached to the wall unless otherwise recommended by the manufacturer of the tub.
(5) Fixture fittings. Faucets and diverters shall be installed so that the flow of hot water from the fittings
corresponds to the left-hand side of the fitting.
(6) Hydromassage bathtub (i)

Access panel. A door or panel of sufficient size must be installed to provide access to the pump
for repair or replacement.

(ii) Piping drainage. The circulation pump must be accessibly located above the crown weir of the
trap. The pump drain line must be properly sloped to drain the volute after fixture use.
(iii) Piping. Hydromassage bathtub circulation piping must be installed to be self-draining.
(iv) Electrical. Wiring must comply with Articles 680.70, 680.71, and 680.72 of the National
Electrical Code, NFPA No. 70-2005.
[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 961, Jan. 4, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at
52 FR 4586, Feb. 12, 1987; 58 FR 55014, Oct. 25, 1993; 70 FR 72049, Nov. 30, 2005; 71 FR 19639, Apr. 17, 2006; 78 FR 73985, Dec.
9, 2013; 79 FR 31863, June 3, 2014]

§ 3280.608 Hangers and supports.
(a) Strains and stresses. Piping in a plumbing system shall be installed without undue strains and stresses,
and provision shall be made for expansion, contraction, and structural settlement.
(b) Piping supports. Piping must be secured at sufficiently close intervals to keep the pipe in alignment and
carry the weight of the pipe and contents. Unless otherwise stated in the standards incorporated by
reference for specific materials at § 3280.604(a), or unless specified by the pipe manufacturer, horizontal
plastic drainage piping must be supported at intervals not to exceed 4 feet and horizontal plastic water
piping must be supported at intervals not to exceed 3 feet. Vertical drainage and water piping must be
supported at each story height.
(c) Hangers and anchors.
(1) Hangers and anchors shall be of sufficient strength to support their proportional share of the pipe
alignments and prevent rattling.
(2) Piping shall be securely attached to the structure by hangers, clamps, or brackets which provide
protection against motion, vibration, road shock, or torque in the chassis.
(3) Hangers and straps supporting plastic pipe shall not compress, distort, cut or abrade the piping and
shall allow free movement of the pipe.
[40 FR 58752, Dec. 18, 1975, as amended at 86 FR 2521, Jan. 12, 2021]

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24 CFR 3280.609

§ 3280.609 Water distribution systems.
(a) Water supply (1) Supply piping. Piping systems shall be sized to provide an adequate quantity of water to each
plumbing fixture at a flow rate sufficient to keep the fixture in a clean and sanitary condition without
any danger of backflow or siphonage. (See table in § 3280.609(f)(1)). The manufacturer shall include
in his written installation instructions that the manufactured home has been designed for an inlet
water pressure of 80 psi, and a statement that when the manufactured home is to be installed in
areas where the water pressure exceeds 80 psi, a pressure reducing valve should be installed.
(2) Hot water supply. Each manufactured home equipped with a kitchen sink, and bathtub and/or shower
shall be provided with a hot water supply system including a listed water heater.
(b) Water outlets and supply connections (1) Water connection. Each manufactured home with a water distribution system shall be equipped with
a 3⁄4 inch threaded inlet connection. This connection shall be tagged or marked “Fresh Water
Connection” (or marked “Fresh Water Fill”). A matching cap or plug shall be provided to seal the
water inlet when it is not in use, and shall be permanently attached to the manufactured home or
water supply piping. When a master cold water shutoff full flow valve is not installed on the main
feeder line in an accessible location, the manufacturer's installation instructions shall indicate that
such a valve is to be installed in the water supply line adjacent to the home. When a manufactured
home includes expandable rooms or is composed of two or more units, fittings or connectors
designed for such purpose shall be provided to connect any water piping. When not connected, the
water piping shall be protected by means of matching threaded caps or plugs.
(2) Prohibited connections.
(i)

The installation of potable water supply piping or fixture or appliance connections shall be
made in a manner to preclude the possibility of backflow.

(ii) No part of the water system shall be connected to any drainage or vent piping.
(3) Rim outlets. The outlets of faucets, spouts, and similar devices shall be spaced at least 1 inch above
the flood level of the fixture.
(4) Appliance connections. Water supplies connected to clothes washing or dishwashing machines shall
be protected by an approved or listed fixed air gap provided within the appliance by the
manufacturer.
(5) Flushometer valves or manually operated flush valves. An approved or listed vacuum breaker shall be
installed and maintained in the water supply line on the discharge side of a water closet flushometer
valve or manually operated flush valve. Vacuum breakers shall have a minimum clearance of 6
inches above the flood level of the fixture to the critical level mark unless otherwise permitted in their
approval.
(6) Flush tanks. Water closet flush tanks shall be equipped with an approved or listed anti-siphon ball
cock which shall be installed and maintained with its outlet or critical level mark not less than 1 inch
above the full opening of the overflow pipe.

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24 CFR 3280.609(b)(7)

(7) Hose bibbs. When provided, all exterior hose bibbs and laundry sink hose connections must be
protected by a listed nonremovable backflow prevention device. This requirement is not applicable to
hose connections provided for automatic washing machines with built-in backflow prevention or
water heater drain valves.
(8) Flushometer tanks. Flushometer tanks must be equipped with an approved air gap or vacuum
breaker assembly that is located above the flood-level rim above the fixture.
(c) Water heater safety devices (1) Relief valves.
(i)

All water heaters shall be installed with approved and listed fully automatic valve or valves
designed to provide temperature and pressure relief.

(ii) Any temperature relief valve or combined pressure and temperature relief valve installed for this
purpose shall have the temperature sensing element immersed in the hottest water within the
upper 6 inches of the tank. It shall be set to start relieving at a pressure of 150 psi or the rated
working pressure of the tank whichever is lower and at or below a water temperature of 210 °F.
(iii) Relief valves must be provided with full-sized drains, with cross sectional areas equivalent to
that of the relief valve outlet. The outlet of a pressure relief valve, temperature relief valve, or
combination thereof, must not be directly connected to the drainage system. The discharge
from the relief valve must be piped full size separately to the exterior of the manufactured
home, not underneath the home, or to an indirect waste receptor located inside the
manufactured home. Exterior relief drains shall be directed down and shall terminate between
6″ and 24″ above finished grade. Drain lines must be of a material listed for hot water
distribution and must drain fully by gravity, must not be trapped, and must not have their outlets
threaded, and the end of the drain must be visible for inspection.
(iv) Relief valve piping designed to be located underneath the manufactured home is not required to
be installed at the factory provided the manufacturer designs the system for site assembly and
also provides all materials and components including piping, fittings, cement, supports, and
instructions for proper site installation.
(d) Materials (1) Piping material. Water pipe shall be of standard weight brass, galvanized wrought iron, galvanized
steel, Type K, L or M copper tubing, approved or listed plastic or other approved or listed material.
(i)

Plastic piping. All plastic water piping and fittings in manufactured homes must be listed for
use with hot water.

(ii) [Reserved]
(2) Fittings. Appropriate fittings shall be used for all changes in size and where pipes are joined. The
material and design of fittings shall conform to the type of piping used. Special consideration shall
be given to prevent corrosion when dissimilar metals are joined.
(i)

Fittings for screw piping shall be standard weight galvanized iron for galvanized iron and steel
pipe, and of brass for brass piping. They shall be installed where required for change in
direction, reduction of size, or where pipes are joined together.

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24 CFR 3280.609(d)(2)(ii)

(ii) Fittings for copper tubing shall be cast brass or drawn copper (sweat-soldered) or shall be
approved or listed fittings for the purpose intended.
(3) Prohibited material. Used piping materials shall not be permitted. Those pipe dopes, solder, fluxes,
oils, solvents, chemicals, or other substances that are toxic, corrosive, or otherwise detrimental to
the water system shall not be used. In addition, for those manufactured homes to be connected to a
public water system, all water piping shall be lead-free (as defined in section 109(c)(2) of the Safe
Drinking Water Act Amendments of 1986) with solders and flux containing not more than 0.2 percent
lead and pipes and pipe fittings containing not more than 8.0 percent lead.
(e) Installation of piping (1) Minimum requirement. All piping equipment, appurtenances, and devices shall be installed in
workmanlike manner and shall conform with the provisions and intent of this standard.
(2) Screw pipe. Iron pipe-size brass or galvanized iron or steel pipe fittings shall be joined with approved
or listed standard pipe threads fully engaged in the fittings. Pipe ends shall be reamed to the full
bore of the pipe. Pipe-joint compound shall be insoluble in water, shall be nontoxic and shall be
applied to male threads only.
(3) Solder fittings. Joints in copper water tubes shall be made by the appropriate use of approved cast
brass or wrought copper fittings, properly soldered together. The surface to be soldered shall be
thoroughly cleaned bright mechanically. The joints shall be properly fluxed and made with a solder
that contains no more than 0.2 percent lead.
(4) Flared fittings. A flaring tool shall be used to shape the ends of flared tubing to match the flare of
fittings.
(5) Plastic pipe and fittings. Plastic pipe and fittings shall be joined by installation methods
recommended by the manufacturer or in accordance with provisions of a listed standard.
(f) Size of water supply piping (1) Minimum size. The size of water supply piping and branch lines shall not be less than sizes shown in
the following table:

Minimum Size Tubing and Pipe for Water Distribution Systems
Number of fixtures

Tubing (nominal)
Diameter (inches)

Pipe iron pipe size (inches)

Outer diameter (inches)

1

* 1⁄4

3⁄

8

1⁄

2

3⁄

2

8

1⁄

2

1⁄

2

3

1⁄

2

5⁄

8

1⁄

4

1⁄

2

2

5⁄

8

1⁄

5 or more

3⁄

2

4

7⁄

8

3⁄

4

*6 ft maximum length.

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24 CFR 3280.609(f)(2)

Exceptions to table: 3⁄8 inch nominal diameter or 1⁄2 inch OD minimum size for clothes washing or
dishwashing machines, unless larger size is recommended by the fixture manufacturer. 1⁄2 inch
nominal diameter or 5⁄8 inch OD minimum size for flushometer or metering type valves unless
otherwise specified in their listing. No galvanized screw piping shall be less than 1⁄2 inch iron pipe
size.
(2) Sizing procedure. Both hot and cold water piping systems shall be computed by the following
method:
(i)

Size of branch. Start at the most remote outlet on any branch of the hot or cold water piping and
progressively count towards the water service connection, computing the total number of
fixtures supplied along each section of piping. Where branches are joined together, the number
of fixtures on each branch shall be totalled so that no fixture is counted twice. Following down
the left-hand column of the preceding table a corresponding number of fixtures will be found.
The required pipe or tubing size is indicated in the other columns on the same line.

(ii) A water heater, food waste disposal unit, evaporative cooler or ice maker shall not be counted
as a water-using fixture when computing pipe sizes.
(g) Line valves. Valves, when installed in the water supply distribution system (except those immediately
controlling one fixture supply) and when fully opened, shall have a cross-sectional area of the smallest
orifice or opening, through which the water flows, at least equal to the cross-sectional area of the nominal
size of the pipe in which the valve is installed.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4586, Feb. 12, 1987; 53 FR 23611,
June 23, 1988; 58 FR 55014, Oct. 25, 1993; 78 FR 73986, Dec. 9, 2013; 86 FR 2521, Jan. 12, 2021]

§ 3280.610 Drainage systems.
(a) General.
(1) Each fixture directly connected to the drainage system shall be installed with a water seal trap (§
3280.606(a)).
(2) The drainage system shall be designed to provide an adequate circulation of air in all piping with no
danger of siphonage, aspiration, or forcing of trap seals under conditions of ordinary use.
(b) Materials (1) Pipe. Drainage piping must be standard weight galvanized steel, brass, copper tube DWV, listed
Scheduled 40 ABS plastic, listed Scheduled 40 PVC plastic, cast iron, or other listed or approved
materials.
(2) Fittings. Drainage fittings shall be recessed drainage pattern with smooth interior waterways of the
same diameter as the piping and shall be of a material conforming to the type of piping used.
Drainage fittings shall be designed to provide for a 1⁄4 inch per foot grade in horizontal piping.
(i)

Fittings for screw pipe shall be cast iron, malleable iron, brass, or listed plastic with standard
pipe threads.

(ii) Fittings for copper tubing shall be cast brass or wrought copper.
(iii) Socket-type fittings for plastic piping shall comply with listed standards.
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24 CFR 3280.610(b)(2)(iv)

(iv) Brass or bronze adaptor or wrought copper fittings shall be used to join copper tubing to
threaded pipe.
(c) Drain outlets.
(1) General. Each manufactured home shall have only one drain outlet.
(2) Clearance from drain outlet. The drain outlet shall be provided with a minimum clearance of 3 inches
in any direction from all parts of the structure or appurtenances and with not less than 18 inches
unrestricted clearance directly in front of the drain outlet.
(3) Drain connector. The drain connector shall not be smaller than the piping to which it is connected and
shall be equipped with a water-tight cap or plug matching the drain outlet. The cap or plug shall be
permanently attached to the manufactured home or drain outlet.
(4) Size Requirement. The drain outlet and drain connector shall not be less than 3 inches inside
diameter.
(5) Preassembly of drain lines. Section(s) of the drain system, designed to be located underneath the
manufactured home or between stories of the manufactured home, are not required to be factory
installed when the manufacturer designs the system for site assembly and also provides all
materials and components, including piping, fittings, cement, supports, and instructions necessary
for proper site installation.
(d) Fixture connections. Drainage piping shall be provided with approved or listed inlet fittings for fixture
connections, correctly located according to the size and type of fixture to be connected.
(1) Water closet connection. The drain connection for each water closet shall be 3 inches minimum
inside diameter and shall be fitted with an iron, brass, or listed plastic floor flange adaptor ring
securely screwed, soldered or otherwise permanently attached to the drain piping, in an approved
manner and securely fastened to the floor.
(2) [Reserved]
(e) Size of drainage piping. Fixture drains must be sized as follows:
(1) Fixture drains serving a single lavatory must be a minimum of 11⁄4 inches in diameter.
(2) Fixture drains serving two or three fixtures must be a minimum of 11⁄2 inches in diameter.
(3) Fixture drains serving four or more fixtures that are individually vented must be a minimum of 2
inches in diameter.
(4) Fixture drains for water closets must be a minimum of 3 inches in diameter.
(f) Wet-vented drainage system. Plumbing fixture traps may connect into a wet-vented drainage system
which shall be designed and installed to accommodate the passage of air and waste in the same pipe.
(1) Horizontal piping. All parts of a wet-vented drainage system, including the connected fixture drains,
shall be horizontal except for wet-vented vertical risers which shall terminate with a 11⁄2 inch
minimum diameter continuous vent. Where required by structural design, wet-vented drain piping
may be offset vertically when other vented fixture drains or relief vents are connected to the drain
piping at or below the vertical offsets.

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24 CFR 3280.610(f)(2)

(2) Size. A wet-vented drain pipe shall be 2 inches minimum diameter and at least one pipe size larger
than the largest connected trap or fixture drain. Not more than three fixtures may connect to a 2-inch
diameter wet-vented drain system.
(3) Length of trap arm. Fixture traps shall be located within the distance given in § 3280.611(c)(5). Not
more than one trap shall connect to a trap arm.
(g) Offsets and branch fittings (1) Changes in direction. Changes in direction of drainage piping shall be made by the appropriate use of
approved or listed fittings, and shall be of the following angles: 111⁄4, 221⁄2, 45, 60, or 90 degrees; or
other approved or listed fittings or combinations of fittings with equivalent radius or sweep.
(2) Horizontal to vertical. Horizontal drainage lines, connecting with a vertical pipe shall enter through
45-degree “Y” branches, 60-degree “Y” branches, long-turn “TY” branches, sanitary “T” branches, or
other approved or listed fittings or combination of fittings having equivalent sweep. Fittings having
more than one branch at the same level shall not be used, unless the fitting is constructed so that
the discharge from any one branch cannot readily enter any other branch. However, a double sanitary
“T” may be used when the drain line is increased not less than two pipe sizes.
(3) Horizontal to horizontal and vertical to horizontal. Horizontal drainage lines connecting with other
horizontal drainage lines or vertical drainage lines connected with horizontal drainage lines shall
enter through 45-degree “Y” branches, long-turn “TY” branches, or other approved or listed fittings or
combination of fittings having equivalent sweep.
(h) Grade of horizontal drainage piping. Except for fixture connections on the inlet side of the trap, horizontal
drainage piping shall be run in practical alignment and have a uniform grade of not less than 1⁄4 inch per
foot toward the manufactured home drain outlet. Where it is impractical, due to the structural features or
arrangement of any manufactured home, to obtain a grade of 1⁄4 inch per foot, the pipe or piping may have
a grade of not less than 1⁄8 inch per foot, when a full size cleanout is installed at the upper end.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4586, Feb. 12, 1987; 58 FR 55015,
Oct. 25, 1993; 78 FR 73986, Dec. 9, 2013; 86 FR 2521, Jan. 12, 2021]

§ 3280.611 Vents and venting.
(a) General. Each plumbing fixture trap shall be protected against siphonage and back pressure, and air
circulation shall be ensured throughout all parts of the drainage system by means of vents installed in
accordance with the requirements of this section and as otherwise required by this standard.
(b) Materials (1) Pipe. Vent piping must be standard weight galvanized steel, brass, copper tube DWV, listed
Scheduled 40 ABS plastic, listed Scheduled 40 PVC plastic, cast iron, or other listed or approved
materials.
(2) Fittings. Appropriate fittings shall be used for all changes in direction or size and where pipes are
joined. The material and design of vent fittings shall conform to the type of piping used.
(i)

Fittings for screw pipe shall be cast iron, malleable iron, plastic, or brass, with standard pipe
threads.

(ii) Fittings for copper tubing shall be cast brass or wrought copper.
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24 CFR 3280.611(b)(2)(iii)

(iii) Fittings for plastic piping shall be made to approved applicable standards.
(iv) Brass adaptor fittings or wrought copper shall be used to join copper tubing to threaded pipe.
(v) Listed rectangular tubing may be used for vent piping only providing it has an open cross
section at least equal to the circular vent pipe required. Listed transition fittings shall be used.
(c) Size of vent piping (1) Main vent. The drain piping for each toilet shall be vented by a 11⁄2 inch minimum diameter vent or
rectangular vent of venting cross section equivalent to or greater than the venting cross section of a
11⁄2 inch diameter vent, connected to the toilet drain by one of the following methods:
A 11⁄2 inch diameter (min.) individual vent pipe or equivalent directly connected to the toilet
drain within the distance allowed in § 3280.611(c)(5), for 3-inch trap arms undiminished in size
through the roof;

(i)

(ii) A 11⁄2-inch diameter (min.) continuous vent or equivalent, indirectly connected to the toilet drain
piping within the distance allowed in paragraph (c)(5) of this section for 3 inch trap arms
through a 2-inch wet vented drain that carries the waste of not more than one fixture. Sections
of the wet vented drain that are 3 inches in diameter are permitted to carry the waste of an
unlimited number of fixtures; or
(iii) Two or more vented drains when at least one is wet-vented, or 2-inch diameter (minimum), and
each drain is separately connected to the toilet drain. At least one of the drains shall connect
within the distance allowed in § 3280.611(c)(5) for 3-inch trap arms.
(2) Vent pipe areas. Each individually vented fixture with a 11⁄2 inch or smaller trap shall be provided with
a vent pipe equivalent in area to a 11⁄4 inch nominal pipe size. The main vent, toilet vent and relief
vent, and the continuous vent of wet-vented systems shall have an area equivalent to 11⁄2 inch
nominal pipe size.
(3) Common vent. When two fixture traps located within the distance allowed from their vent have their
trap arms connected separately at the same level into an approved double fitting, an individual vent
pipe may serve as a common vent without any increase in size.
(4) Intersecting vents. Where two or more vent pipes are joined together, no increase in size shall be
required; however, the largest vent pipe shall extend full size through the roof.
(5) Distance of fixture trap from vent shall not exceed the values given in the following table:

Maximum Distance of Fixtures From Vent Trap
Size of fixture drain (inches)

Distance trap to vent

1 1⁄

4

4 ft. 6 in.

1 1⁄

2

4 ft 6 in.

2

5 ft.

3

6 ft.

(d) Mechanical Vents. Where mechanical vents are used as a secondary vent system for plumbing fixtures
that are protected by traps, the mechanical vents must comply with paragraphs (d)(1) or (2) of this
section.
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24 CFR 3280.611(d)(1)

(1) Spring-operated mechanical (anti-siphon) vents must comply with the following:
(i)

No more than two fixtures individually protected by the spring-operated mechanical vent may be
drained by a common 11⁄2 inch diameter drain.

(ii) The drain size for three or more fixtures individually protected by a spring-operated mechanical
vent must be at least 2 inches in diameter.
(iii) Spring-operated mechanical vents are restricted to venting fixtures with 11⁄2 inch traps.
(iv) A spring-operated mechanical vent must be installed in a location that allows a free flow of air
and is accessible for inspection, maintenance, and replacement. The sealing function must be
at least 6 inches above the top of the trap arm.
(v) Materials for the spring-operated mechanical vents must be as follows:
(A) Cap and housing must be listed acrylonitrile-butadiene-styrene, DWV grade;
(B) Stem must be DWV grade nylon or acetal;
(C) Spring must be stainless steel wire, Type 302; and
(D) Sealing disc must be either:
(1) Neoprene, conforming to CISPI-HSN-85, Specification for Neoprene Rubber Gaskets
for HUB and Spigot Cast Iron Soil Pipe and Fittings (incorporated by reference, see §
3280.4), and to ASTM C564-97, Standard Specification for Rubber Gaskets for Cast
Iron Soil Pipe and Fittings (incorporated by reference, see § 3280.4); or
(2) Other material, conforming to ASTM C920-02, Standard Specification for Elastomeric
Joint Sealants (incorporated by reference, see § 3280.4), and to ASTM D4635-01,
Standard Specification for Polyethylene Films Made from Low-Density Polyethylene
for General Use and Packaging Applications (incorporated by reference, see §
3280.4).
(2) Gravity-operated mechanical (air admittance valves) vents must comply with the following:
(i)

Where installed to vent any fixture, the drain system must have a minimum 11⁄2 inch diameter
vent that terminates outside the manufactured home.

(ii) Where gravity-operated mechanical vent devices terminate in the attic cavity, the following
requirements must be met:
(A) The attic cavity must be accessible;
(B) The sealing device must be installed a minimum of 6 inches above the insulation
materials; and
(C) The attic must be vented in accordance with § 3280.504(c)(1)(i);
(3) Mechanical vents must be installed in accordance with the vent manufacturer's instructions.
(e) Grade and connections (1) Horizontal vents. Each vent shall extend vertically from its fixture “T” or point of connection with the
waste piping to a point not less than 6 inches above the extreme flood level of the fixture it is venting
before offsetting horizontally or being connected with any other vent pipe. Vents for horizontal
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24 CFR 3280.611(f)

drains shall connect above the centerline of the drain piping ahead (downstream) of the trap. Where
required by structural conditions, vent piping may offset below the rim of the fixture at the maximum
angle or height possible.
(f) Vent terminal. Vents must terminate through the roof or wall, or to a mechanical vent device in accordance
with paragraph (d) of this section.
(1) Roof extension. Each vent pipe must extend through its flashing and terminate vertically. Vents that
extend through the roof must extend undiminished in size, not less than 2 inches above the roof.
Vent openings must be at least 3 feet away from any motor-driven air intake that opens into any
habitable area.
(2) Wall extensions. Extensions through exterior walls must terminate downward, have a screen to
prevent entrance of birds and rodents, and be located as follows:
(i)

Extensions must not be located beneath a door, window, or other opening;

(ii) Extensions must be a minimum of 10 feet above the finished floor;
(iii) Extensions must be located a minimum of 2 feet above any building opening that is within 10
feet horizontally of any extension; and
(iv) Extensions must not terminate under an overhang with soffit vents.
(3) Flashing. The opening around each vent pipe shall be made watertight by an adequate flashing or
flashing material.
(g) Vent caps. Vent caps, if provided, shall be of the removable type (without removing the flashing from the
roof). When vent caps are used for roof space ventilation and the caps are identical to vent caps used for
the plumbing system, plumbing system caps shall be identified with permanent markings.
[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 961, Jan. 4, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at
58 FR 55015, Oct. 25, 1993; 78 FR 73986, Dec. 9, 2013; 86 FR 2521, Jan. 12, 2021]

§ 3280.612 Tests and inspection.
(a) Water system. All water piping in the water distribution system must be subjected to a pressure test. The
test must be made by subjecting the system to air or water at 80 psi + or − 5 psi for 15 minutes without
loss of pressure. The water used for the test must be obtained from a potable water source.
(b) Drainage and vent system and plumbing fixtures. The waste and vent system shall be tested by one of the
three following alternate methods for evidence or indication of leakage:
(1) Water test. Before plumbing fixtures are connected, all of the openings into the piping shall be
plugged and the entire piping system subjected to a static water test for 15 minutes by filling it with
water to the top of the highest vent opening. There shall be no evidence of leakage.
(2) Air test. After all fixtures have been installed, the traps filled with water, and the remaining openings
securely plugged, the entire system shall be subjected to a 2-inch (manometer) water column air
pressure test. If the system loses pressure, leaks may be located with smoke pumped into the
system, or with soap suds spread on the exterior of the piping (Bubble test).

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24 CFR 3280.612(b)(3)

(3) Flood level test. The manufactured home shall be in a level position, all fixtures shall be connected,
and the entire system shall be filled with water to the rim of the water closet bowl. (Tub and shower
drains shall be plugged). After all trapped air has been released, the test shall be sustained for not
less than 15 minutes without evidence of leaks. Then the system shall be unplugged and emptied.
The waste piping above the level of the water closet bowl shall then be tested and show no
indication of leakage when the high fixtures are filled with water and emptied simultaneously to
obtain the maximum possible flow in the drain piping.
(c) Fixture test. The plumbing fixtures and connections shall be subjected to a flow test by filling them with
water and checking for leaks and retarded flow while they are being emptied.
(d) Shower compartments. Shower compartments and receptors shall be tested for leaks prior to being
covered by finish material. Each pan shall be filled with water to the top of the dam for not less than 15
minutes without evidence of leakage.
[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 961, Jan. 4, 1977; 42 FR 54383, Oct. 5, 1977. Redesignated at 44 FR 20679,
Apr. 6, 1979, as amended at 58 FR 55015, Oct. 25, 1993; 86 FR 2521, Jan. 12, 2021]

Subpart H - Heating, Cooling and Fuel Burning Systems
§ 3280.701 Scope.
Subpart H of this standard covers the heating, cooling and fuel burning equipment installed within, on, or external to
a manufactured home.

§ 3280.702 Definitions.
The definitions in this subpart apply to subpart H only.
Accessible, when applied to a fixture, connection, appliance or equipment, means having access thereto, but
which may require the removal of an access panel, door or similar obstruction.
Air conditioner blower coil system means a comfort cooling appliance where the condenser section is placed
external to the manufactured home and evaporator section with circulating blower attached to the
manufactured home air supply duct system. Provision must be made for a return air system to the
evaporator/blower section. Refrigerant connection between the two parts of the system is accomplished
by tubing.
Air conditioner split system means a comfort cooling appliance where the condenser section is placed external
to the manufactured home and the evaporator section incorporated into the heating appliance or with a
separate blower/coil section within the manufactured home. Refrigerant connection between the two
parts of the system is accomplished by tubing.
Air conditioning condenser section means that portion of a refrigerated air cooling or (in the case of a heat
pump) heating system which includes the refrigerant pump (compressor) and the external heat
exchanger.
Air conditioning evaporator section means a heat exchanger used to cool or (in the case of a heat pump) heat air
for use in comfort cooling (or heating) the living space.

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24 CFR 3280.702 “Air conditioning self contained system”

Air conditioning self contained system means a comfort cooling appliance combining the condenser section,
evaporator and air circulating blower into one unit with connecting ducts for the supply and return air
systems.
Air duct means conduits or passageways for conveying air to or from heating, cooling, air conditioning or
ventilation equipment, but not including the plenum.
Automatic pump (oil lifter) means a pump, not an integral part of the oil-burning appliance, that automatically
pumps oil from the supply tank and delivers the oil under a constant head to an oil-burning appliance.
Btu. British thermal units means the quantity of heat required to raise the temperature of one pound of water one
degree Fahrenheit.
Btuh means British thermal units per hour.
Burner means a device for the final conveyance of fuel or a mixture of fuel and air to the combustion zone.
Central air conditioning system means either an air conditioning split system or an external combination
heating/cooling system.
Class 0 air ducts and air connectors means air ducts and air connectors having a fire hazard classification of
zero when tested in accordance with UL 181-2003, Factory-Made Air Ducts and Air Connectors
(incorporated by reference, see § 3280.4).
Class 1 air ducts and air connectors means air ducts and air connectors having a flame spread rating of not over
25 without evidence of continued progressive combustion and a smoke developed rating of not over 50
when tested in accordance with UL 181-2003, Standard for Safety Factory-Made Air Ducts and Air
Connectors (incorporated by reference, see § 3280.4).
Clearance means the distance between the appliance, chimney, vent, chimney or vent connector or plenum and
the nearest surface.
Combination space heating and water heating appliance means a listed unit that is designed to provide space
heating and water heating from a single primary energy source.
Connector-Gas appliance: means a flexible or semi-rigid connector used to convey fuel gas between a gas outlet
and a gas appliance.
Direct-vent system means a system or method of construction where all air for combustion is derived directly
from the outside atmosphere and all flue gases are discharged to the outside atmosphere.
Direct-vent system appliance means an appliance that is installed with a direct vent system.
External combination heating/cooling system means a comfort conditioning system placed external to the
manufactured home with connecting ducts to the manufactured home for the supply and return air
systems.
Factory-built fireplace means a hearth, fire chamber and chimney assembly composed of listed factory-built
components assembled in accordance with the terms of listing to form a complete fireplace.
Fireplace stove means a chimney connected solid fuel-burning stove having part of its fire chamber open to the
room.
Fuel gas piping system means the arrangement of piping, tubing, fittings, connectors, valves and devices
designed and intended to supply or control the flow of fuel gas to the appliance(s).
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24 CFR 3280.702 “Fuel oil piping system”

Fuel oil piping system means the arrangement of piping, tubing, fittings, connectors, valves and devices
designed and intended to supply or control the flow of fuel oil to the appliance(s).
Gas clothes dryer means a device used to dry wet laundry by means of heat derived from the combustion of fuel
gases.
Gas refrigerator means a gas-burning appliance which is designed to extract heat from a suitable chamber.
Gas supply connection means the terminal end or connection to which a gas supply connector is attached.
Gas supply connector, manufactured home means a listed flexible connector designed for connecting the
manufactured home to the gas supply source.
Gas vents means factory-built vent piping and vent fittings listed by an approved testing agency, that are
assembled and used in accordance with the terms of their listings, for conveying flue gases to the outside
atmosphere.
(1) Type B gas vent means a gas vent for venting gas appliances with draft hoods and other gas
appliances listed for use with Type B gas vents.
(2) Type BW gas vent means a gas vent for venting listed gas-fired vented wall furnaces.
Heat producing appliance means all heating and cooking appliances and fuel burning appliances.
Heating appliance means an appliance for comfort heating, domestic water heating, or a combination of
comfort heating and domestic water heating.
Liquefied petroleum gases. The terms Liquefied petroleum gases, LPG and LP-Gas as used in this standard shall
mean and include any material which is composed predominantly of any of the following hydrocarbons, or
mixtures of them: propane, propylene butanes (normal butane or isobutane), and butylenes.
Plenum means an air compartment which is part of an air-distributing system, to which one or more ducts or
outlets are connected.
(1) Furnace supply plenum is a plenum attached directly to, or an integral part of, the air supply outlet of
the furnace.
(2) Furnace return plenum is a plenum attached directly to, or an integral part of, the return inlet of the
furnace.
Quick-disconnect device means a hand-operated device which provides a means for connecting and
disconnecting a gas supply or connecting gas systems and which is equipped with an automatic means
to shut off the gas supply when the device is disconnected.
Readily accessible means direct access without the necessity of removing any panel, door, or similar
obstruction.
Roof jack means that portion of a manufactured home heater flue or vent assembly, including the cap, insulating
means, flashing, and ceiling plate, located in and above the roof of a manufactured home.
Sealed combustion system appliance means an appliance which by its inherent design is constructed so that all
air supplied for combustion, the combustion system of the appliance, and all products of combustion are
completely isolated from the atmosphere of the space in which it is installed.
Water heater means an appliance for heating water for domestic purposes.

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24 CFR 3280.703

[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4586, Feb. 12, 1987; 58 FR 55015,
Oct. 25, 1993; 78 FR 73987, Dec. 9, 2013]

§ 3280.703 Minimum standards.
Heating, cooling and fuel burning appliances and systems in manufactured homes shall be free of defects, and shall
conform to applicable standards in the following table unless otherwise specified in this standard. (See § 3280.4)
When more than one standard is referenced, compliance with any one such standard shall meet the requirements of
this standard.

Appliances
Heating and Cooling Equipment, Second Edition, with 1999 revisions - UL 1995, 1995.
Liquid Fuel-Burning Heating Appliances for Manufactured Homes and Recreational Vehicles, Seventh Edition,
with 1997 revisions - UL 307A-1995.
Fixed and Location-Dedicated Electric Room Heaters, Second Edition, with 1998 revisions - UL 2021-1997.
Electric Baseboard Heating Equipment, Fourth Edition, with 1998 revisions - UL 1042-1994.
Electric Central Air Heating Equipment - UL 1096-Fourth Edition-1986 with revisions July 16, 1986, and January
30, 1988.
Gas Burning Heating Appliances for Manufactured Homes and Recreational Vehicles, Fourth Edition, with 1998
revisions - UL 307B-1995.
Gas Clothes Dryers Volume 1, Type 1 Clothes Dryers - ANSI Z21.5.1-/CSA 7.1-M99 - 1999 with Addendum
Z21.5.1a-1999.
Gas Fired Absorption Summer Air Conditioning Appliances - ANSI Z21.40.1/CGA 2.91-M961996.
Gas-Fired Central Furnaces (Except Direct Vent System Central Furnaces) - ANSI Z21.47-1990 with Addendum
Z21.47a-1990 and Z21.47b-1992.
Decorative Gas Appliances for Installation in Solid Fuel Burning Fireplaces - RADCO DS-010-91 (incorporated by
reference, see § 3280.4).
Household Cooking Gas Appliances - ANSI Z21.1-2000.
Refrigerators Using Gas Fuel - ANSI Z21.19-1990, with Addendum ANSI Z21.19a-1992 and Z21.19b-1995.
Gas Water Heaters - Volume 1, Storage Water Heaters with Input Ratings of 75,000 BTU per hour or Less - ANSI
Z21.10.1-1998 with Addendum Z21.10.1a-2000.
Household Electric Storage Tank Water Heaters, Tenth Edition - UL 174-1996, with 1997 revisions.

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24 CFR 3280.703

Ferrous Pipe and Fittings
Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless - ASTM
A53-93.
Standard Specification for Electric-Resistance-Welded Coiled Steel Tubing for Gas and Fuel Oil Lines - ASTM
A539-1999.
Pipe Threads, General Purpose (Inch) - ANSI/ASME B1.20.1-1983.
Welding and Seamless Wrought Steel Pipe - ANSI/ASME B36.10-1979.

Nonferrous Pipe, Tubing, and Fittings
Standard Specification for Seamless Copper Water Tube - ASTM B88-93.
Standard Specification for Seamless Copper Tube for Air Conditioning and Refrigeration Field Service - ASTM
B280-95a.
Connectors for Gas Appliances - ANSI Z21.24/CGA 6.10-M97-1997.
Manually Operated Gas Valves for Appliances, Appliance Connector Valves and Hose End Valves - ANSI
Z21.15/CGA 9.1-M97-1997.
Standard for Gas Supply Connectors for Manufactured Homes - IAPMO TSC 9-1997.
Standard Specification for General Requirements for Wrought Seamless Copper and Copper-Alloy Tubes ASTM B251-93.
Standard Specification for Seamless Copper Pipe, Standard Sizes - ASTM B42-93.

Miscellaneous
Factory-Made Air Ducts and Air Connectors, UL 181, Ninth Edition, April 4, 1996, with revisions through May 15,
2003 (incorporated by reference, see § 3280.4).
Standard for Safety Closure Systems for use with Rigid Air Ducts and Air Connectors, UL 181A, 1994, with 1998
revisions.
Standard for Safety Closure Systems for use with Flexible Air Ducts and Air Connectors, First Edition - UL 181B,
1995, with 1998 revisions.
Tube Fittings for Flammable and Combustible Fluids, Refrigeration Service, and Marine Use, Sixth Edition - UL
109-1997, with 2001 revisions.
Pigtails and Flexible Hose Connectors for LP-Gas, Seventh Edition - UL 569, 1995 with 2001 revisions.

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24 CFR 3280.704

Roof Jacks for Manufactured Homes and Recreational Vehicles, Eighth Edition - UL 311, 1994, with 1998
revisions.
Relief Valves for Hot Water Supply Systems, ANSI Z21.22-1999, (incorporated by reference, see § 3280.4).
Automatic Gas Ignition Systems and Components - ANSI Z21.20 with Addendum Z21.20a-2000.
Automatic Valves for Gas Appliances - ANSI Z21.21/CSA 6.5-2000.
Gas Appliance Thermostats - ANSI Z21.23-93 (incorporated by reference, see § 3280.4).
Gas Vents, Ninth Edition - UL 441, 1996 with 1999 revisions.
Standard for the Installation of Oil-Burning Equipment, NFPA 31-01 (incorporated by reference, see § 3280.4).
National Fuel Gas Code - NFPA 54-2002/ANSI Z223.1-2002.
Warm Air Heating and Air Conditioning Systems, NFPA 90B, 1996 Edition.
Liquefied Petroleum Gas Code, NFPA 58-2001 Edition.
Flares for Tubing - SAE-J533b-1992.
Factory-Built Chimneys for Residential Type and Building Heating Appliances, Ninth Edition - UL 103, 1995, with
1999 revisions.
Factory-Built Fireplaces, Seventh Edition - UL 127-1996, with 1999 revisions.
Solid-Fuel Type Room Heaters, Fifth Edition - UL 1482, 1995, with 2000 revisions.
Fireplace Stoves, Eight Edition, with 2000 revisions - UL 737, 1996.
Unitary Air-Conditioning and Air-Source Heat Pump Equipment - ANSI/ARI 210/240-89.
AGA Requirements for Gas Connectors for Connection of Fixed Appliances for Outdoor Installation, Park
Trailers, and Manufactured (Mobile) Homes to the Gas Supply - No. 3-87.
[58 FR 55015, Oct. 25, 1993, as amended at 70 FR 72046, Nov. 30, 2005; 78 FR 73987, Dec. 9, 2013]

§ 3280.704 [Reserved]
§ 3280.705 Gas piping systems.
(a) General. The requirements of this section shall govern the installation of all fuel gas piping attached to
any manufactured home. The gas piping supply system shall be designed for a pressure not exceeding 14
inch water column (1⁄2 psi) and not less than 7 inch water column (1⁄4 psi). The manufacturer shall
indicate in his written installation instructions the design pressure limitations for safe and effective
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24 CFR 3280.705(b)

operation of the gas piping system. None of the requirements listed in this section shall apply to the
piping supplied as a part of an appliance. All exterior openings around piping, ducts, plenums or vents
shall be sealed to resist the entrance of rodents.
(b) Materials. All materials used for the installation, extension, alteration, or repair of any gas piping system
shall be new and free from defects or internal obstructions. It shall not be permissible to repair defects in
gas piping or fittings. Inferior or defective materials shall be removed and replaced with acceptable
material. The system shall be made of materials having a melting point of not less than 1,450 F, except as
provided in § 3280.705(e). They shall consist of one or more of the materials described in § 3280.705(b)
(1) through (4).
(1) Steel or wrought-iron pipe shall comply with ANSI Standard B36.10-1979, Welded and Seamless
Wrought Steel Pipe. Threaded brass pipe in iron pipe sizes may be used. Threaded brass pipe shall
comply with ASTM B43-91, Standard Specification for Seamless Red Brass Pipe, Standard Sizes.
(2) Fittings for gas piping shall be wrought iron, malleable iron, steel, or brass (containing not more than
75 percent copper).
(3) Copper tubing must be annealed type, Grade K or L, conforming to the Standard Specification for
Seamless Copper Water Tube, ASTM B88-93, or must comply with the Standard Specification for
Seamless Copper Tube for Air Conditioning and Refrigeration Service, ASTM B280-1995. Copper
tubing must be internally tinned.
(4) Steel tubing must have a minimum wall thickness of 0.032 inch for tubing of 1⁄2 inch diameter and
smaller and 0.049 inch for diameters 1⁄2 inch and larger. Steel tubing must be in accordance with
ASTM Standard Specification for Electric-Resistance-Welded Coiled Steel Tubing for Gas and Fuel Oil
Lines, ASTM A539-1999, and must be externally corrosion protected.
(5) Corrugated stainless steel tubing (CSST) systems must be listed and installed in accordance with
ANSI/IAS LC-1-1997, Fuel Gas Piping Systems Using Corrugated Stainless Steel Tubing (CSST)
(incorporated by reference, see § 3280.4), and the requirements of this section.
(c) Piping design. Each manufactured home requiring fuel gas for any purpose shall be equipped with a
natural gas piping system acceptable for LP-gas. Where fuel gas piping is to be installed in more than one
section of an expandable or multiple unit home, the design and construction of the crossover(s) shall be
as follows:
(1) All points of crossover beneath the transportable sections must be readily accessible from the
exterior of the home. In multi-story manufactured homes, the interconnections between stories must
be accessible through a panel on the exterior or interior of the manufactured home.
(2) The connection(s) between units must be made with a connector(s) listed for exterior use or direct
plumbing sized in accordance with § 3280.705(d). A shutoff valve of the non-displaceable rotor type
conforming to ANSI Z21.15-1997, Manually Operated Gas Valves for Appliances, Appliances
Connector Valves, and Hose End Valves, suitable for outdoor use must be installed at each
crossover point upstream of the connection.
(3) The connection(s) may be made by a listed quick disconnect device which shall be designed to
provide a positive seal of the supply side of the gas system when such device is separated.
(4) The flexible connector, direct plumbing pipe, or “quick disconnect” device shall be provided with
protection from mechanical and impact damage and located to minimize the possibility of
tampering.
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24 CFR 3280.705(c)(5)

(5) For gas line cross over connections made with either hard pipe or flexible connectors, the crossover
point(s) shall be capped on the supply side to provide a positive seal and covered on the other side
with a suitable protective covering.
(6) Suitable protective coverings for the connection device(s) when separated, shall be permanently
attached to the device or flexible connector.
(7) When a quick disconnect device is installed, a 3 inch by 13⁄4 inch minimum size tag made of etched,
metal-stamped or embossed brass, stainless steel, anodized or alcalde aluminum not less than
0.020 inch thick or other approved material (e.g., 0.005 inch plastic laminates) shall be permanently
attached on the exterior wall adjacent to the access to the “quick disconnect” device. Each tag shall
be legibly inscribed with the following information using letters no smaller than 1⁄4 inch high:

DO NOT USE TOOLS TO SEPARATE THE “QUICK-DISCONNECT” DEVICE
(d) Gas pipe sizing. Gas piping systems shall be sized so that the pressure drop to any appliance inlet
connection from any gas supply connection, when all appliances are in operation at maximum capacity, is
not more than 0.5 inch water column as determined on the basis of test, or in accordance with table
3280.705(d). When determining gas pipe sizing in the table, gas shall be assumed to have a specific
gravity of 0.65 and rated at 1000 B.T.U. per cubic foot. The natural gas supply connection(s) shall be not
less than the size of the gas piping but shall be not smaller than 3⁄4 inch nominal pipe size.

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24 CFR 3280.705(d)

Table to paragraph (d) - Maximum Capacity of Different Sizes of Pipe and Tubing in Thousands of Btu/hr of Natural
Gas for Gas Pressures of 0.5 psig or Less, and a Maximum Pressure Drop of 1⁄2 in. Water Column
ID (in.) 10 ft 20 ft 30 ft 40 ft 50 ft 60 ft 70 ft 80 ft 90 ft 100 ft
Iron Pipe Sizes - Length
1⁄

4

43

29

24

20

18

16

15

14

13

12

3⁄

8

95

65

52

45

40

36

33

31

29

27

1⁄

2

175

120

97

82

73

66

61

57

53

50

3⁄

4

360

250

200

170

151

138

125

118

110

103

680

465

375

320

285

260

240

220

215

195

1

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24 CFR 3280.705(d)

EHD2 ID (in.) 10 ft 20 ft 30 ft 40 ft 50 ft 60 ft 70 ft 80 ft 90 ft 100 ft
Corrugated Stainless Steel Tubing - Length1
13

3⁄

8

31

21

17

14

13

12

11

10

10

9

15

3⁄

8

42

30

24

20

18

16

15

14

13

12

18

1⁄

2

79

56

45

39

36

33

30

28

27

25

19

1⁄

2

91

64

52

45

40

36

35

32

31

29

23

3⁄

4

155

111

92

80

72

65

60

58

55

52

25

3⁄

30
31
37

4

184

132

108

93

84

77

71

66

62

60

1

317

222

180

156

138

126

116

108

103

97

1

368

258

209

180

161

147

135

127

120

113

598

426

350

304

273

250

231

217

205

195

1 1⁄

4

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24 CFR 3280.705(d)

OD (in.) 10 ft 20 ft 30 ft 40 ft 50 ft 60 ft 70 ft 80 ft 90 ft 100 ft
Copper Tubing - Length
1⁄

4

27

18

15

13

11

10

9

9

8

8

3⁄

8

56

38

31

26

23

21

19

18

17

16

1⁄

2

113

78

62

53

47

43

39

37

34

33

3⁄

4

197

136

109

93

83

75

69

64

60

57

280

193

155

132

117

106

98

91

85

81

1
1

Includes losses for four 90-degree bends and two end fittings. Tubing runs with larger numbers of bend and/or fittings shall be increased by an equivalent
length of tubing according to the following equation: L = 1.3n, where L is actual length (ft) of tubing and n is the number of additional fittings and/or bends.
2

EHD (Equivalent Hydraulic Diameter) - A measure of the hydraulic efficiency between different tubing sizes.

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24 CFR 3280.705(e)

(e) Joints for gas pipe. All pipe joints in the piping system, unless welded or brazed, shall be threaded joints
that comply with Pipe Threads, General Purpose (Inch), adopted 25 October 1984, ANSI/ASME
B1.20.1-1983. Right and left nipples or couplings shall not be used. Unions, if used, shall be of ground
joint type. The material used for welding or brazing pipe connections shall have a melting temperature in
excess of 1,000 F.
(f) Joints for tubing.
(1) Tubing joints shall be made with either a single or a double flare of 45 degrees in accordance with
Flares For Tubing, SAE-J533b-1992 or with other listed vibration-resistant fittings, or joints may be
brazed with material having a melting point exceeding 1,000 °F. Metallic ball sleeve compressiontype tubing fittings shall not be used.
(2) Steel tubing joints shall be made with a double-flare in accordance with Flares For Tubing, SAEJ533b-1972.
(g) Pipe joint compound. Screw joints shall be made up tight with listed pipe joint compound, insoluble in
liquefied petroleum gas, and shall be applied to the male threads only.
(h) Concealed tubing.
(1) Copper tubing must not be run inside walls, floors, partitions, or roofs. Corrugated stainless steel
tubing (CSST) may be run inside walls, floors, partitions, and roofs under the following conditions:
(i)

The CSST is protected from accidental puncture by a steel strike barrier not less than 0.058 inch
thick, or the barrier's equivalent, installed between the tubing and the finished wall and
extending 4 inches beyond concealed penetrations of plates, firestops, and wall studs, or
specified by the tubing manufacturer's instructions; and

(ii) The CSST is installed in single runs and is not rigidly secured.
(2) Where tubing passes through exterior walls, floors, partitions, or similar construction, the tubing
must be protected by the use of weather-resistant grommets that snugly fit both the tubing and the
hole through which the tubing passes, or protected as specified in the tubing manufacturer's
instructions.
(3) Concealed joints: Piping or tubing joints must not be located in any wall, floor, partition, or similar
concealed construction space.
(i)

Concealed joints. Piping or tubing joints shall not be located in any floor, wall partition, or similar
concealed construction space.

(j)

Gas supply connections. When gas appliances are installed, at least one gas supply connection must be
provided on each home. The connection must not be located beneath an exit door. Where more than one
connection is provided, the piping system must be sized to provide adequate capacity from each supply
connection.

(k) Identification of gas supply connections. Each manufactured home must have permanently affixed to the
exterior skin at or near each gas supply connection or the end of the pipe, a tag of 3 inches by 13⁄4 inches
minimum size, made of etched, metal-stamped or embossed brass, stainless steel, anodized or alcalde
aluminum not less than 0.020 inch thick, or other approved material [e.g., 0.005 inch plastic laminates],
with the information shown in Figure 1 to this paragraph (k). The connector capacity indicated on this tag
must be equal to or greater than the total Btu/hr rating of all intended gas appliances.
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(l)

24 CFR 3280.705(l)

LP-gas supply connectors.
(1) A listed LP-Gas flexible connection conforming to UL 569-1995, Pigtails and Flexible Hose
Connectors for LP Gas, or equal must be supplied when LP-Gas cylinders(s) and regulator(s) are
supplied.
(2) Appliance connections. All gas burning appliances shall be connected to the fuel piping. Materials as
provided in § 3280.705(b) or listed appliance connectors shall be used. Listed appliance connectors
when used shall not run through walls, floors, ceilings or partitions, except for cabinetry, and shall be
3 feet or less in length or 6 feet or less for cooking appliances. Connectors of aluminum shall not be
used outdoors. A manufactured home containing a combination LP-natural-gas-system may be
provided with a gas outlet to supply exterior appliances when installed in accordance with the
following:
(i)

No portion of the completed installation shall project beyond the wall of the manufactured
home.

(ii) The outlet must be provided with an approved quick-disconnect device, which must be
designed to provide a positive seal on the supply side of the gas system when the appliance is
disconnected. A shutoff valve of the non-displaceable rotor type conforming to ANSI
Z21.15-1997, Manually Operated Gas Valves, must be installed immediately upstream of the
quick-disconnect device. The complete device must be provided as part of the original
installation.
(iii) Protective caps or plugs for the “quick-disconnect” device, when disconnected, shall be
permanently attached to the manufactured home adjacent to the device.
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24 CFR 3280.705(l)(2)(iv)

(iv) A tag shall be permanently attached to the outside of the exterior wall of the manufactured
home as close as possible to the gas supply connection. The tag shall indicate the type of gas
and the Btuh capacity of the outlet and shall be legibly inscribed as follows:
THIS OUTLET IS DESIGNED FOR USE WITH GAS PORTABLE APPLIANCES WHOSE TOTAL INPUT DO
NOT EXCEED ______ BTUH. REPLACE PROTECTIVE COVERING OVER CONNECTOR WHEN NOT IN
USE.
(3) Valves. A shutoff valve must be installed in the fuel piping at each appliance inside the manufactured
home structure, upstream of the union or connector in addition to any valve on the appliance and so
arranged to be accessible to permit servicing of the appliance and removal of its components. The
shutoff valve must be located within 6 feet of any cooking appliance and within 3 feet of any other
appliance. A shutoff valve may serve more than one appliance if located as required by this
paragraph (3). The shutoff valve must be of the non-displaceable rotor type and conform to ANSI
Z21.15-1997, Manually Operated Gas Valves.
(4) Gas piping system openings. All openings in the gas piping system shall be closed gas-tight with
threaded pipe plugs or pipe caps.
(5) Electrical ground. Gas piping shall not be used for an electrical ground.
(6) Couplings. Pipe couplings and unions shall be used to join sections of threaded piping. Right and left
nipples or couplings shall not be used.
(7) Hangers and supports. All horizontal gas piping must be adequately supported by galvanized or
equivalently protected metal straps or hangers at intervals of not more than 4 feet, except where
adequate support and protection is provided by structural members. Vertical gas piping in multistory dwelling units must be supported at intervals of not more than 6 feet. Solid iron-pipe
connection(s) must be rigidly anchored to a structural member within 6 inches of the supply
connection(s).
(8) Testing for leakage.
(i)

Before appliances are connected, piping systems must stand a pressure of three ± 0.2 psi
gauge for a period of not less than ten minutes without showing any drop in pressure. Pressure
must be measured with a mercury manometer or slope gauge calibrated so as to be read in
increments of not greater than one-tenth pound, or an equivalent device. The source of normal
operating pressure must be isolated before the pressure tests are made. Before a test is begun,
the temperature of the ambient air and of the piping must be approximately the same, and
constant air temperature must be maintained throughout the test.

(ii) After appliances are connected, the piping system shall be pressurized to not less than 10
inches nor more than 14 inches water column and the appliance connections tested for
leakage with soapy water or bubble solution.
(iii) Where gas piping between transportable sections must be made on site, the installation
instructions must contain provisions for onsite testing for leakage consistent with the
provisions in paragraph (l)(8)(i) of this section.
[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 54383, Oct. 5, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended
at 52 FR 4587, Feb. 12, 1987; 58 FR 55016, Oct. 25, 1993; 70 FR 72050, Nov. 30, 2005; 78 FR 73987, Dec. 9, 2013; 86 FR 2522,
Jan. 12, 2021]
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24 CFR 3280.706

§ 3280.706 Oil piping systems.
(a) General. The requirements of this section shall govern the installation of all liquid fuel piping attached to
any manufactured home. None of the requirements listed in this section shall apply to the piping in the
appliance(s).
(b) Materials. All materials used for the installation extension, alteration, or repair, of any oil piping systems
shall be new and free from defects or internal obstructions. The system shall be made of materials having
a melting point of not less than 1,450 F, except as provided in § 280.706(d) and (e). They shall consist of
one or more of the materials described in § 3280.706(b) (1) through (4).
(1) Steel or wrought-iron pipe shall comply with ANSI B 36.10-1979, Welded and Seamless Wrought
Steel Pipe. Threaded copper or brass pipe in iron pipe sizes may be used.
(2) Fittings for oil piping shall be wrought-iron, malleable iron, steel, or brass (containing not more than
75 percent copper).
(3) Copper tubing must be annealed type, Grade K or L conforming to the Standard Specification for
Seamless Copper Water Tube, ASTM B88-93, or shall comply with ASTM B280-1995, Standard
Specification for Seamless Copper Tube for Air Conditioning and Refrigeration Field Service.
(4) Steel tubing shall have a minimum wall thickness of 0.032 inch for diameters up to 1⁄2 inch and 0.049
inch for diameters 1⁄2 inch and larger. Steel tubing shall be constructed in accordance with the
Specification for Electric-Resistance-Welded Coiled Steel Tubing for Gas and Field Oil Lines, ASTM,
A539-90a, and shall be externally corrosion protected.
(c) Size of oil piping. The minimum size of all fuel oil tank piping connecting outside tanks to the appliance
shall be no smaller than 3⁄8 inch OD copper tubing or 1⁄4 inch IPS. If No. 1 fuel oil is used with a listed
automatic pump (fuel lifter), copper tubing shall be sized as specified by the pump manufacturer.
(d) Joints for oil piping. All pipe joints in the piping system, unless welded or brazed, shall be threaded joints
which comply with ANSI/ASME B1.20.1-1983, Pipe Threads, General Purpose (Inch). The material used
for brazing pipe connections shall have a melting temperature in excess of 1,000 F.
(e) Joints for tubing. Joints in tubing shall be made with either a single or double flare of the proper degree,
as recommended by the tubing manufacturer, by means of listed tubing fittings, or brazed with materials
having a melting point in excess of 1,000 F.
(f) Pipe joint compound. Threaded joints shall be made up tight with listed pipe joint compound which shall
be applied to the male threads only.
(g) Couplings. Pipe couplings and unions shall be used to join sections of threaded pipe. Right and left
nipples or couplings shall not be used.
(h) Grade of piping. Fuel oil piping installed in conjunction with gravity feed systems to oil heating equipment
shall slope in a gradual rise upward from a central location to both the oil tank and the appliance in order
to eliminate air locks.
(i)

Strap hangers. All oil piping shall be adequately supported by galvanized or equivalently protected metal
straps or hangers at intervals of not more than 4 feet, except where adequate support and protection is
provided by structural members. Solid-iron-pipe oil supply connection(s) shall be rigidly anchored to a
structural member within 6 inches of the supply connection(s).

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(j)

24 CFR 3280.706(j)

Testing Tag. A tag must be affixed to each oil-fired appliance stating: “Before setting the system in
operation, tank installations and piping must be checked for oil leaks with fuel oil of the same grade that
will be burned in the appliance. No other material may be used for testing fuel oil tanks and piping. Tanks
must be filled to maximum capacity for the final check for oil leakage.”

[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4588, Feb. 12, 1987; 58 FR 55017,
Oct. 25, 1993; 70 FR 72050, Nov. 30, 2005; 78 FR 73988, Dec. 9, 2013]

§ 3280.707 Heat producing appliances.
(a) Heat-producing appliances and vents, roof jacks and chimneys necessary for their installation in
manufactured homes shall be listed or certified by a nationally recognized testing agency for use in
manufactured homes.
(1) A manufactured home shall be provided with a comfort heating system.
(i)

When a manufactured home is manufactured to contain a heating appliance, the heating
appliance shall be installed by the manufacturer of the manufactured home in compliance with
applicable sections of this subpart.

(ii) When a manufactured home is manufactured for field application of an external heating or
combination heating/cooling appliance, preparation of the manufactured home for this external
application shall comply with the applicable sections of this part.
(2) Each gas and oil burning comfort heating appliance must have an Annual Fuel Utilization Efficiency
of not less than that specified in 10 CFR part 430, Energy Conservation Program for Consumer
Products: Test Procedures for Furnaces/Boilers, Vented Home Heating Equipment and Pool Heaters.
(b) Fuel-burning heat-producing appliances and refrigeration appliances, except ranges and ovens, shall be of
the vented type and vented to the outside.
(c) Fuel-burning appliances shall not be converted from one fuel to another fuel unless converted in
accordance with the terms of their listing and the appliance manufacturer's instructions.
(d) Performance efficiency. Each automatic storage water heater must comply with the efficiency
requirements of 10 CFR part 430, Energy Conservation Program for Consumer Products: Energy
Conservation Standards for Water Heaters.
(1) All automatic electric storage water heaters installed in manufactured homes shall have a standby
loss not exceeding 43 watts/meter2 (4 watts/ft2) of tank surface area. The method of test for
standby loss shall be as described in section 4.3.1 of Household Automatic Electric Storage Type
Water Heaters, ANSI C72.1-1972.

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24 CFR 3280.707(d)(2)

(2) All gas and oil-fired automatic storage water heaters shall have a recovery efficiency, E, and a
standby loss, S, as described below. The method of test of E and S shall be as described in section
2.7 of Gas Water heaters, Vol. I, Storage Water Heaters with Input/Ratings of 75,000 BTU per hour or
less, ANSI Z21.10.1-1998 with addendums Z21.10.1a-2000, and Z21.10.1b-1992, except that for oilfired units. CF = 1.0, Q = total gallons of oil consumed and H = total heating value of oil in BTU/
gallon.
Storage capacity in
gallons

Recovery
efficiency

Standby loss

Less than 25

At least 75 percent.

Not more than 7.5 percent.

25 up to 35

00

Not more than 7 percent.

35 or more

00

Not more than 6 percent.

(e) Each space heating, cooling or combination heating and cooling system shall be provided with at least
one readily adjustable automatic control for regulation of living space temperature. The control shall be
placed a minimum of 3 feet from the vertical edge of the appliance compartment door. It shall not be
located on an exterior wall or on a wall separating the appliance compartment from a habitable room.
(f) Oil-fired heating equipment. All oil-fired heating equipment must conform to Liquid Fuel-burning Heating
Appliances for Manufactured Homes and Recreational Vehicles, UL 307A-1995, with 1997 revisions, and
be installed in accordance with Standard for the Installation of Oil Burning Equipment, NFPA 31-01
(incorporated by reference, see § 3280.4). Regardless of the requirements of the above-referenced
standards, or any other standards referenced in this part, the following are not required:
(1) External switches or remote controls which shut off the burner or the flow of oil to the burner, or
(2) An emergency disconnect switch to interrupt electric power to the equipment under conditions of
excessive temperature.
[40 FR 58752, Dec. 17, 1975, as amended at 42 FR 54383, Oct. 5, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended
at 47 FR 49391, Nov. 1, 1982; 52 FR 4588, Feb. 12, 1987; 52 FR 47553, Dec. 15, 1987; 58 FR 55017, Oct. 25, 1993; 70 FR 72050,
Nov. 30, 2005; 78 FR 73988, Dec. 9, 2013]

§ 3280.708 Exhaust duct system and provisions for the future installation of a clothes dryer.
(a) Clothes dryers.
(1) All gas and electric clothes dryers must be exhausted to the outside by a moisture/lint exhaust duct
and termination fitting. When the manufacturer supplies the clothes dryer, the exhaust duct and
termination fittings must be completely installed by the manufacturer. If the exhaust duct system is
subject to damage during transportation, or a field connection between transportable sections is
required, complete factory installation of the exhaust duct system is not required when the following
apply:
(i)

The exhaust duct system is connected to the clothes dryer, and

(ii) A moisture lint exhaust duct system is roughed in and installation instructions are provided in
accordance with paragraph (b)(3) or (c) of this section.
(2) A clothes dryer moisture-lint exhaust duct shall not be connected to any other duct, vent or chimney.
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24 CFR 3280.708(a)(3)

(3) The exhaust duct shall not terminate beneath the manufactured home.
(4) Moisture-lint exhaust ducts shall not be connected with sheet metal screws or other fastening
devices which extend into the interior of the duct.
(5) Moisture-lint exhaust duct and termination fittings shall be installed in accordance with the appliance
manufacturer's printed instructions.
(b) Provisions for future installation of a gas clothes dryer. A manufactured home may be provided with
“stubbed in” equipment at the factory to supply a gas clothes dryer for future installation by the owner
provided it complies with the following provisions:
(1) The “stubbed in” gas outlet shall be provided with a shutoff valve, the outlet of which is closed by
threaded pipe plug or cap;
(2) The “stubbed in” gas outlet shall be permanently labeled to identify it for use only as the supply
connection for a gas clothes dryer;
(3) A moisture lint duct system consisting of a complete access space (hole) through the wall or floor
cavity with a cap or cover on the interior and exterior of the cavity secured in such a manner that
they can be removed by a common household tool shall be provided. The cap or cover in place shall
limit air infiltration and be designed to resist the entry of water or rodents. The manufacturer is not
required to provide the moisture-lint exhaust duct or the termination fitting. The manufacturer shall
provide written instructions to the owner on how to complete the exhaust duct installation in
accordance with provisions of § 3280.708(a)(1) through (5).
(c) Provisions for future installation of electric clothes dryers. When wiring is installed to supply an electric
clothes dryer for future installation by the owner, the manufacturer shall:
(1) Provide a roughed in moisture-lint exhaust duct system consisting of a complete access space
(hole) through the wall or floor cavity with a cap or cover on the interior and exterior of the cavity
which are secured in such a manner that they can be removed by the use of common household
tools. The cap or cover in place shall limit air filtration and be designed to resist the entry of water or
rodents into the home. The manufacturer is not required to provide the moisture-lint exhaust duct or
the termination fitting;
(2) Install a receptacle for future connection of the dryer;
(3) Provide written instructions on how to complete the exhaust duct installation in accordance with the
provisions of paragraphs (a)(1) through (5) of this section.
[42 FR 54383, Oct. 5, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55018, Oct. 25, 1993; 86 FR 2522,
Jan. 12, 2021]

§ 3280.709 Installation of appliances.
(a) The installation of each appliance must conform to the terms of its listing and the manufacturer's
instructions. The manufactured home manufacturer must leave the appliance manufacturer's instructions
attached to the appliance. Every appliance must be secured in place to avoid displacement. For the
purpose of servicing and replacement, each appliance must be both accessible and removable.
(1) A direct vent space heating appliance is permitted to be shipped loose for on-site installation in a
basement provided the following:
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(i)

24 CFR 3280.709(a)(1)(i)

The heating appliance is listed for the installation.

(ii) Approved installation instructions are provided that include requirements for completion of all
gas and electrical connections and provide for the manufacturer's inspection and/or testing of
all connections.
(iii) Approved instructions are provided to assure connection of the vent and combustion air
systems in accordance with § 3280.710(b), and to provide for the manufacturer's inspection of
the systems for compliance.
(iv) Approved installation and the manufacturer's inspection procedures are provided for the
connection of the site-installed heating appliance to the factory-installed circulation air system
and return air systems.
(2) The procedures must include revisions to assure compliance of the installed systems with §
3280.715.
(b) Heat-producing appliances shall be so located that no doors, drapes, or other such material can be placed
or swing closer to the front of the appliance than the clearances specified on the labeled appliances.
(c) Clearances surrounding heat producing appliances shall not be less than the clearances specified in the
terms of their listings.
(1) Prevention of storage. The area surrounding heat producing appliances installed in areas with
interior or exterior access shall be framed-in or guarded with noncombustible material such that the
distance from the appliance to the framing or guarding material is not greater than three inches
unless the appliance is installed in compliance with paragraph (c)(2), of this section. When clearance
required by the listing is greater than three inches, the guard or frame shall not be closer to the
appliance than the distance provided in the listing.
(2) Clearance spaces surrounding heat producing appliances are not required to be framed-in or guarded
when:
(i)

A space is designed specifically for a clothes washer or dryer;

(ii) Dimensions surrounding the appliance do not exceed three inches; or
(iii) The manufacturer affixes either to a side of an alcove or compartment containing the appliance,
or to the appliance itself, in a clearly visible location, a 3″ × 5″ adhesive backed plastic
laminated label or the equivalent which reads as follows:

“WARNING”
This compartment is not to be used as a storage area. Storage of combustible materials or
containers on or near any appliance in this compartment may create a fire hazard. Do not store such
materials or containers in this compartment.
(d) All fuel-burning appliances, except ranges, ovens, illuminating appliances, clothes dryers, solid fuelburning fireplaces and solid fuel-burning fireplace stoves, shall be installed to provide for the complete
separation of the combustion system from the interior atmosphere of the manufactured home.
Combustion air inlets and flue gas outlets shall be listed or certified as components of the appliance. The
required separation may be obtained by:
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24 CFR 3280.709(d)(1)

(1) The installation of direct vent system (sealed combustion system) appliances, or
(2) The installation of appliances within enclosures so as to separate the appliance combustion system
and venting system from the interior atmosphere of the manufactured home. There shall not be any
door, removable access panel, or other opening into the enclosure from the inside of the
manufactured home. Any opening for ducts, piping, wiring, etc., shall be sealed.
(e) A forced air appliance and its return-air system shall be designed and installed so that negative pressure
created by the air-circulating fan cannot affect its or another appliance's combustion air supply or act to
mix products of combustion with circulating air.
(1) The air circulating fan of a furnace installed in an enclosure with another fuel-burning appliance shall
be operable only when any door or panel covering an opening in the furnace fan compartment or in a
return air plenum or duct is in the closed position. This does not apply if both appliances are direct
vent system (sealed combustion system) appliances.
(2) If a warm air appliance is installed within an enclosure to conform to § 3280.709(d)(2), each warmair outlet and each return air inlet shall extend to the exterior of the enclosure. Ducts, if used for that
purpose, shall not have any opening within the enclosure and shall terminate at a location exterior to
the enclosure.
(3) Cooling coils installed as a portion of, or in connection with, any forced-air furnace shall be installed
on the downstream side unless the furnace is specifically otherwise listed.
(4) An air conditioner evaporator section shall not be located in the air discharge duct or plenum of any
forced-air furnace unless the manufactured home manufacturer has complied with certification
required in § 3280.511.
(5) If a cooling coil is installed with a forced-air furnace, the coil shall be installed in accordance with its
listing. When a furnace-coil unit has a limited listing, the installation must be in accordance with that
listing.
(6) When an external heating appliance or combination cooling/heating appliance is to be field installed,
the home manufacturer shall make provision for proper location of the connections to the supply
and return air systems. The manufacturer is not required to provide said appliance(s). The
preparation by the manufacturer for connection to the home's supply and return air system shall
include all fittings and connection ducts to the main duct and return air system such that the installer
is only required to provide:
(i)

The appliance;

(ii) Any appliance connections to the home; and
(iii) The connecting duct between the external appliance and the fitting installed on the home by the
manufacturer. The above connection preparations by the manufacturer do not apply to supply
or return air systems designed only to accept external cooling (i.e., self contained air
conditioning systems, etc.)
(7) The installation of a self contained air conditioner comfort cooling appliance shall meet the following
requirements:

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(i)

24 CFR 3280.709(e)(7)(i)

The installation on a duct common with an installed heating appliance shall require the
installation of an automatic damper or other means to prevent the cooled air from passing
through the heating appliance unless the heating appliance is certified or listed for such
application and the supply system is intended for such an application.

(ii) The installation shall prevent the flow of heated air into the external cooling appliance and its
connecting ducts to the manufactured home supply and return air system during the operation
of the heating appliance installed in the manufactured home.
(iii) The installation shall prevent simultaneous operation of the heating and cooling appliances.
(f) Vertical clearance above cooking top. Ranges shall have a vertical clearance above the cooking top of not
less than 24 inches. (See § 3280.204).
(g) Solid fuel-burning factory-built fireplaces and fireplace stoves listed for use in manufactured homes may
be installed in manufactured homes provided they and their installation conform to the following
paragraphs. A fireplace or fireplace stove shall not be considered as a heating facility for determining
compliance with subpart F.
(1) A solid fuel-burning fireplace or fireplace stove shall be equipped with integral door(s) or shutter(s)
designed to close the fireplace or fireplace stove fire chamber opening and shall include complete
means for venting through the roof, a combustion air inlet, a hearth extension, and means to securely
attach the fireplace or the fireplace stove to the manufactured home structure. The installation shall
conform to the following paragraphs (g)(1) (i) to (vii) inclusive:
(i)

A listed factory-built chimney designed to be attached directly to the fireplace or fireplace stove
shall be used. The listed factory built chimney shall be equipped with and contain as part of its
listing a termination device(s) and a spark arrester(s).

(ii) A fireplace or fireplace stove, air intake assembly, hearth extension and the chimney shall be
installed in accordance with the terms of their listings and their manufacturer's instructions.
(iii) The combustion air inlet shall conduct the air directly into the fire chamber and shall be
designed to prevent material from the hearth dropping onto the area beneath the manufactured
home.
(iv) The fireplace or fireplace stove shall not be installed in a sleeping room.
(v) Hearth extension shall be of noncombustible material not less than 3⁄8-inch thick. The hearth
shall extend at least 16 inches in front or and at least 8 inches beyond each side of the fireplace
or fireplace stove opening. Furthermore the hearth shall extend over the entire surface beneath
a fireplace stove and beneath an elevated or overhanging fireplace.
(vi) The label on each solid fuel-burning fireplace and solid fuel-burning fireplace stove shall include
the following wording: For use with solid fuel only.
(vii) The chimney shall extend at least three feet above the part of the roof through which it passes
and at least two feet above the highest elevation of any part of the manufactured home within
10 feet of the chimney. Portions of the chimney and termination that exceed an elevation of
131⁄2 ft. above ground level may be designed to be removed for transporting the manufactured
home.

24 CFR 3280.709(g)(1)(vii) (enhanced display)

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24 CFR 3280.709(h)

(h) A corrosion resistant water drip collection and drain pan must be installed under each water heater that
will allow water leaking from the water heater to drain to the exterior of the manufactured home, or to a
drain.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 44 FR 66195, Nov. 19, 1979; 58 FR 55018,
Oct. 25, 1993; 70 FR 72050, Nov. 30, 2005; 86 FR 2523, Jan. 12, 2021]

§ 3280.710 Venting, ventilation and combustion air.
(a) The venting as required by § 3280.707(b) shall be accomplished by one or more of the methods given in
(a)(1) and (2) of this section:
(1) An integral vent system listed or certified as part of the appliance.
(2) A venting system consisting entirely of listed components, including roof jack, installed in
accordance with the terms of the appliance listing and the appliance manufacturer's instructions.
(b) Venting and combustion air systems shall be installed in accordance with the following:
(1) Components shall be securely assembled and properly aligned at the factory in accordance with the
appliance manufacturer's instructions except vertical or horizontal sections of a fuel fired heating
appliance venting system that extend beyond the roof line or outside the wall line may be installed at
the site. Sectional venting systems shall be listed for such applications and installed in accordance
with the terms of their listings and manufacturers' instructions. In cases where sections of the
venting system are removed for transportation, a label shall be permanently attached to the
appliance indicating the following:
Sections of the venting system have not been installed. Warning-do not operate the appliance until all
sections have been assembled and installed in accordance with the manufacturer's instructions.
(2) Draft hood connectors shall be firmly attached to draft hood outlets or flue collars by sheet metal
screws or by equivalent effective mechanical fasteners.
(3) Every joint of a vent, vent connector, exhaust duct and combustion air intake shall be secure and in
alignment.
(c) Venting systems shall not terminate underneath a manufactured home.
(d) Venting systems of fuel-burning appliances must terminate at least three feet above any motor-driven air
intake discharging into habitable rooms when located within ten feet of the air intake.
(e) The area in which cooking appliances are located shall be ventilated by a metal duct which may be single
wall, not less than 12.5 square inches in cross-sectional area (minimum dimension shall be two inches)
located above the appliance(s) and terminating outside the manufactured home, or by listed mechanical
ventilating equipment discharging outside the home, that is installed in accordance with the terms of
listing and the manufacturer's instructions. Gravity or mechanical ventilation shall be installed within a
horizontal distance of not more than ten feet from the vertical front of the appliance(s).
(f) Mechanical ventilation which exhausts directly to the outside atmosphere from the living space of a home
shall be equipped with an automatic or manual damper. Operating controls shall be provided such that
mechanical ventilation can be separately operated without directly energizing other energy consuming
devices.
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24 CFR 3280.711

[49 FR 32012, Aug. 9, 1984, as amended at 58 FR 55018, Oct. 25, 1993; 86 FR 2523, Jan. 12, 2021]

§ 3280.711 Instructions.
Operating instructions must be provided with each appliance. The operating and installation instructions for each
appliance must be provided with the homeowner's manual.
[78 FR 73989, Dec. 9, 2013]

§ 3280.712 Marking.
(a) Information on clearances, input rating, lighting and shutdown shall be attached to the appliances with the
same permanence as the nameplate, and so located that it is easily readable when the appliance is
properly installed or shutdown for transporting of manufactured home.
(b) Each fuel-burning appliance shall bear permanent marking designating the type(s) of fuel for which it is
listed.

§ 3280.713 Accessibility.
Every appliance shall be accessible for inspection, service, repair, and replacement without removing permanent
construction. For those purposes, inlet piping supplying the appliance shall not be considered permanent
construction. Sufficient room shall be available to enable the operator to observe the burner, control, and ignition
means while starting the appliance.
[58 FR 55018, Oct. 25, 1993]

§ 3280.714 Appliances, cooling.
(a) Every air conditioning unit or a combination air conditioning and heating unit shall be listed or certified by
a nationally recognized testing agency for the application for which the unit is intended and installed in
accordance with the terms of its listing.
(1) Mechanical air conditioners shall be rated in accordance with the ARI Standard 210/240-89 Unitary
Air Conditioning and Air Source Unitary Heat Pump Equipment (incorporated by reference, see §
3280.4) and certified by ARI or other nationally recognized testing agency capable of providing
follow-up service.
(i)

Electric motor-driven unitary air-cooled air conditioners and heat pumps in the cooling mode
with rated capacity less than 65,000 BTU/hour (19,045 watts), when rated at ARI standard
rating conditions in ARI Standard 210/240-89, Unitary Air-Conditioning and Air-Source Heat
Pump Equipment, must have seasonal energy efficiency (SEER) values not less than as
specified in 10 CFR Part 430, Energy Conservation Program for Consumer Products: Central Air
Conditioners and Heat Pumps Energy Conservation Standards.

(ii) Heat pumps must be certified to comply with all requirements of the ARI Standard 210/240-89,
Unitary Air Conditioning and Air-Source Heat Pump Equipment. Electric motor-driven vapor
compression heat pumps with supplemental electrical resistance heat must be sized to provide
by compression at least 60 percent of the calculated annual heating requirements for the
manufactured home being served. A control must be provided and set to prevent operation of
supplemental electrical resistance heat at outdoor temperatures above 40 °F (4 °C), except for
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24 CFR 3280.714(a)(1)(iii)

defrost conditions. Electric motor-driven vapor compression heat pumps with supplemental
electric resistance heat conforming to ARI Standard 210/240-89, Unitary Air-Conditioning and
Air-Source Heat Pump Equipment, must have Heating Season Performance Factor (HSPF)
efficiencies not less than as specified in the 10 CFR Part 430, Energy Conservation Program for
Consumer Products: Central Air Conditioners and Heat Pumps Energy Conservation Standards.
(iii) Electric motor-driven vapor compression heat pumps with supplemental electric resistance
heat conforming to ARI Standard 210/240-89 Unitary Air-Conditioning and Air-Source Heat
Pump Equipment shall show coefficient of performance ratios not less than shown below:

COP
Temperature degrees
fahrenheit

Coefficient of performance

47

2.5

17

1.7

0

1.0

(2) Gas fired absorption air conditioners must be listed or certified in accordance with ANSI
Z21.40.1-1996, Gas Fired, Heat Activated, Air Conditioning and Heat Pump Appliances (incorporated
by reference, see § 3280.4), and certified by a nationally recognized testing agency capable of
providing follow-up service.
(3) Direct refrigerating systems serving any air conditioning or comfort-cooling system installed in a
manufactured home shall employ a type of refrigerant that ranks no lower than Group 5 in the
Underwriters' Laboratories, Inc. “Classification of Comparative Life Hazard of Various Chemicals.”
(4) When a cooling or heat pump coil and air conditioner blower are installed with a furnace or heating
appliance, they shall be tested and listed in combination for heating and safety performance by a
nationally recognized testing agency.
(5) Cooling or heat pump indoor coils and outdoor sections shall be certified, listed and rated in
combination for capacity and efficiency by a nationally recognized testing agency(ies). Rating
procedures shall be based on U.S. Department of Energy test procedures.
(b) Installation and instructions.
(1) The installation of each appliance shall conform to the terms of its listing as specified on the
appliance and in the manufacturer's instructions. The installer shall include the manufacturer's
installation instructions in the manufactured home. Appliances shall be secured in place to avoid
displacement and movement from vibration and road shock.
(2) Operating instructions shall be provided with the appliance.
(c) Fuel-burning air conditioners shall also comply with § 280.707.
(d) The appliance rating plate shall be so located that it is easily readable when the appliance is properly
installed.
(e) Every installed appliance shall be accessible for inspection, service, repair and replacement without
removing permanent construction.
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24 CFR 3280.715

[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55018, Oct. 25, 1993; 70 FR 72051,
Nov. 30, 2005; 78 FR 73989, Dec. 9, 2013]

§ 3280.715 Circulating air systems.
(a) Supply system.
(1) Supply air ducts, fittings, and any dampers contained therein must be made of galvanized steel, tinplated steel, or aluminum, or must be listed as Class 0 or Class 1 air ducts and air connectors in
accordance with UL 181-2003, Factory-Made Air Ducts and Air Connectors (incorporated by
reference, see § 3280.4). Class 1 air ducts and air connectors must be located at least 3 feet from
the furnace bonnet or plenum. Air connectors must not be used for exterior manufactured home
duct connection. A duct system integral with the structure must be of durable construction that can
be demonstrated to be equally resistant to fire and deterioration as required by this section. Furnace
supply plenums must be constructed of metal that extends a minimum of 3 feet from the heat
exchanger measured along the centerline of airflow. Ducts constructed from sheet metal must be in
accordance with the following table:

Minimum Metal Thickness for Ducts1
Duct type
Round

Diameter 14 in. or less

Width over 14 in.
0.013

0.016

Enclosed rectangular

.013

.016

Exposed rectangular

.016

.019

1

When “nominal” thicknesses are specified, 0.003 in. shall be added to these “minimum” metal
thicknesses.
(2) Sizing of ducts for heating.
(i)

Ducts shall be so designed that when a labeled forced-air furnace is installed and operated
continuously at its normal heating air circulating rate in the manufactured home, with all
registers in the full open position, the static pressure measured in the casing shall not exceed
90% of that shown on the label of the appliance. For upflow furnaces the static pressure shall
be taken in the duct plenum. For external heating or combination heating/cooling appliances
the static pressure shall be taken at the point used by the agency listing or certifying the
appliance.

(ii) When an evaporator-coil specifically designed for the particular furnace is installed between the
furnace and the duct plenum, the total static pressure shall be measured downstream of the
coil in accordance with the appliance label and shall not exceed 90 percent of that shown on
the label of the appliance.
(iii) When any other listed air-cooler coil is installed between the furnace and the duct plenum, the
total static pressure shall be measured between the furnace and the coil and it shall not exceed
90 percent of that shown on the label of the furnace.
(iv) The minimum dimension of any branch duct shall be at least 11⁄2 inches, and of any main duct,
21⁄2 inches.
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24 CFR 3280.715(a)(3)

(3) Sizing of ducts.
(i)

The manufactured home manufacturer shall certify the capacity of the air cooling supply duct
system for the maximum allowable output of ARI certified central air conditioning systems. The
certification shall be at operating static pressure of 0.3 inches of water or greater. (See §
3280.511).

(ii) The refrigerated air cooling supply duct system including registers must be capable of handling
at least 300 cfm per 10,000 btuh with a static pressure no greater than 0.3 inches of water
when measured at room temperature. In the case of application of external self contained
comfort cooling appliances or the cooling mode of combination heating/cooling appliances,
either the external ducts between the appliance and the manufactured home supply system
shall be considered part of, and shall comply with the requirements for the refrigerated air
cooling supply duct system, or the connecting duct between the external appliance and the
mobile supply duct system shall be a part of the listed appliance. The minimum dimension of
any branch duct shall be at least 11⁄2 inches, and of any main duct, 21⁄2 inches.
(4) Airtightness of supply duct systems. A supply duct system shall be considered substantially airtight
when the static pressure in the duct system, with all registers sealed and with the furnace air
circulator at high speed, is at least 80 percent of the static pressure measured in the furnace casing,
with its outlets sealed and the furnace air circulator operating at high speed. For the purpose of this
paragraph and § 3280.715(b) pressures shall be measured with a water manometer or equivalent
device calibrated to read in increments not greater than 1⁄10 inch water column.
(5) Expandable or multiple manufactured home connections.
(i)

An expandable or multiple manufactured home may have ducts of the heating system installed
in the various units. The points of connection must be so designed and constructed that when
the manufactured home is fully expanded or coupled, the resulting duct joint will conform to the
requirements of this part.

(ii) The manufacturer must provide installation instructions for supporting, mechanically fastening,
sealing, and insulating each crossover duct. The instructions must indicate that no portion of
the crossover duct is to be in contact with the ground, and must describe the means to support
the duct without compressing the insulation and restricting airflow.
(6) Air supply ducts shall be insulated with material having an effective thermal resistance (R) of not
less than 4.0 unless they are within manufactured home insulation having a minimum effective value
of R-4.0 for floors or R-6.0 for ceilings.
(7) Unless installed in a basement, supply and return ducts, fittings, and crossover duct plenums
exposed directly to outside air, such as those under-chassis crossover ducts or ducts connecting
external heating, cooling, or combination heating/cooling appliances, must be insulated with
material having a minimum thermal resistance of R-8 in all Thermal Zones. All such insulating
materials must have a continuous vapor barrier retarder having a perm rating of not more than 1
perm. Where ducts are exposed underneath the manufactured home, they must comply with
paragraph (a)(5)(ii) of this section, and shall be listed for exterior use.
(b) Return air systems (1) Return air openings. Provisions shall be made to permit the return of circulating air from all rooms
and living spaces, except toilet room(s), to the circulating air supply inlet of the furnace.
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24 CFR 3280.715(b)(2)

(2) Duct material. Return ducts and any diverting dampers contained therein shall be in accordance with
the following:
(i)

Portions of return ducts directly above the heating surfaces, or closer than 2 feet from the outer
jacket or casing of the furnace shall be constructed of metal in accordance with §
3280.715(a)(1) or shall be listed Class 0 or Class 1 air ducts.

(ii) Return ducts, except as required by paragraph (a) of this section, shall be constructed of oneinch (nominal) wood boards (flame spread classification of not more than 200), other suitable
material no more flammable than one-inch board or in accordance with § 3280.715(a)(1).
(iii) The interior of combustible ducts shall be lined with noncombustible material at points where
there might be danger from incandescent particles dropped through the register or furnace
such as directly under floor registers and the bottom return.
(iv) Factory made air ducts used for connecting external heating, cooling or combination heating/
cooling appliances to the supply system and return air system of a manufactured home shall
be listed by a nationally recognized testing agency. Ducts applied to external heating
appliances or combination heating/cooling appliances supply system outlets shall be
constructed of metal in accordance with § 3280.715(a)(1) or shall be listed Class 0 or Class 1
air ducts for those portions of the duct closer than 2 feet from the outer casing of the
appliance.
(v) Ducts applied to external appliances shall be resistant to deteriorating environmental effects,
including but not limited to ultraviolet rays, cold weather, or moisture and shall be resistant to
insects and rodents.
(3) Sizing. The cross-sectional areas of the return air duct shall not be less than 2 square inches for
each 1,000 Btu per hour input rating of the appliance. Dampers shall not be placed in a combination
fresh air intake and return air duct so arranged that the required cross-sectional area will not be
reduced at all possible positions of the damper.
(4) Permanent uncloseable openings. Living areas not served by return air ducts or closed off from the
return opening of the furnace by doors, sliding partitions, or other means shall be provided with
permanent uncloseable openings in the doors or separating partitions to allow circulated air to
return to the furnace. Such openings may be grilled or louvered. The net free area of each opening
shall be not less than 1 square inch for every 5 square feet of total living area closed off from the
furnace by the door or partition serviced by that opening. Undercutting doors connecting the closedoff space may be used as a means of providing return air area. However, in the event that doors are
undercut, they shall be undercut a minimum of 2 inches and not more than 21⁄2 inches, as measured
from the top surface of the floor decking to the bottom of the door and no more than one half of the
free air area so provided shall be counted as return air area.
(c) Joints and seams. Joints and seams of sheet metal and factory-made flexible ducts, including trunks,
branches, risers, crossover ducts, and crossover duct plenums, shall be mechanically secured and made
substantially airtight. Slip joints in sheet metal ducts shall have a lap of at least one inch and shall be
mechanically fastened. Tapes or caulking compounds shall be permitted to be used for sealing
mechanically secure joints. Sealants and tapes shall be applied only to surfaces that are dry and dust-,
dirt-, oil-, and grease-free. Tapes and mastic closure systems for use with factory-made rigid fiberglass air
ducts and air connectors shall be listed in accordance with UL Standard 181A-1994, with 1998 revisions.
Tapes and mastic closure systems used with factory-made flexible air ducts and air connectors shall be
listed in accordance with UL Standard 181B-1995, with 1998 revisions.
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24 CFR 3280.715(d)

(d) Supports and protection. Ducts must be securely supported. Nails or other fasteners must not be driven or
penetrate through duct walls. Where vertical ducts are installed within closets or rooms, they must be
enclosed with materials equivalent to those used in the closet or room construction.
(e) Registers and grilles. Fittings connecting the registers and grilles to the duct system must be constructed
of metal or material that complies with the requirements of Class 1 or 2 ducts under UL 181-1996 with
1998 revisions, Factory Made Air Ducts and Connectors. Air supply terminal devices (registers) when
installed in kitchen, bedrooms, and bathrooms must be equipped with adjustable closeable dampers.
Registers or grilles must be constructed of metal or conform with the following:
(1) Be made of a material classified 94V-0 or 94V-1, when tested as described in UL 94-1996, with 2001
revisions, Test for Flammability of Plastic Materials for Parts in Devices and Appliances, Fifth
Edition; and
(2) Floor registers or grilles shall resist without structural failure a 200 lb. concentrated load on a 2-inch
diameter disc applied to the most critical area of the exposed face of the register or grille. For this
test the register or grille is to be at a temperature of not less than 165 °F and is to be supported in
accordance with the manufacturer's instructions.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4589, Feb. 12, 1987; 58 FR 55019,
Oct. 25, 1993; 70 FR 72051, Nov. 30, 2005; 78 FR 73989, Dec. 9, 2013]

Subpart I - Electrical Systems
§ 3280.801 Scope.
(a) Subpart I of this part and Part II of Article 550 of the National Electrical Code (NFPA No. 70-2005) cover
the electrical conductors and equipment installed within or on manufactured homes and the conductors
that connect manufactured homes to a supply of electricity.
(b) In addition to the requirements of this part and Part II of Article 550 of the National Electrical Code (NFPA
No. 70-2005), the applicable portions of other Articles of the National Electrical Code must be followed
for electrical installations in manufactured homes. The use of arc-fault breakers under Articles 210.12(A)
and (B), 440.65, and 550.25(A) and (B) of the National Electrical Code, NFPA No. 70-2005 is not required.
However, if arc-fault breakers are provided, such use must be in accordance with the National Electrical
Code, NFPA No. 70-2005. Wherever the requirements of this standard differ from the National Electrical
Code, these standards apply.
(c) The provisions of this standard apply to manufactured homes intended for connection to a wiring system
nominally rated 120/240 volts, 3-wire AC, with grounded neutral.
(d) All electrical materials, devices, appliances, fittings and other equipment shall be listed or labeled by a
nationally recognized testing agency and shall be connected in an approved manner when in service.
(e) Aluminum conductors, aluminum alloy conductors, and aluminum core conductors such as copper clad
aluminum; are not acceptable for use in branch circuit wiring in manufactured homes.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55019, Oct. 25, 1993; 70 FR 72051,
Nov. 30, 2005; 71 FR 19639, Apr. 17, 2006]

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24 CFR 3280.802

§ 3280.802 Definitions.
(a) The following definitions are applicable to subpart I only.
(1) Accessible
(i)

(As applied to equipment) means admitting close approach because not guarded by locked
doors, elevation, or other effective means. (See readily accessible.)

(ii) (As applied to wiring methods) means capable of being removed or exposed without damaging
the manufactured home structure or finish, or not permanently closed-in by the structure or
finish of the manufactured home (see concealed and exposed).
(2) Air conditioning or comfort cooling equipment means all of that equipment intended or installed for
the purpose of processing the treatment of air so as to control simultaneously its temperature,
humidity, cleanliness, and distribution to meet the requirements of the conditioned space.
(3)
(i)

Appliance means utilization equipment, generally other than industrial, normally built in
standardized sizes or types, which is installed or connected as a unit to perform one or more
functions, such as clothes washing, air conditioning, food mixing, deep frying, etc.

(ii) Appliance, fixed means an appliance which is fastened or otherwise secured at a specific
location.
(iii) Appliance, portable means an appliance which is actually moved or can easily be moved from
one place to another in normal use. For the purpose of this Standard, the following major
appliances are considered portable if cord-connected: refrigerators, clothes washers,
dishwashers without booster heaters, or other similar appliances.
(iv) Appliance, stationary means an appliance which is not easily moved from one place to another
in normal use.
(4) Attached accessory building or structure means any awning, cabana, deck, ramada, storage cabinet,
carport, windbreak, garage, or porch for which the attachment of such is designed by the home
manufacturer to be structurally supported by the manufactured home.
(5) Attachment plug (plug cap) (cap) means a device which, by insertion in a receptacle, establishes
connection between the conductors of the attached flexible cord and the conductors connected
permanently to the receptacle.
(6) Bonding means the permanent joining of metallic parts to form an electrically conductive path which
will assure electrical continuity and the capacity to conduct safely any current likely to be imposed.
(7) Branch circuit
(i)

means the circuit conductors between the final overcurrent device protecting the circuit and the
outlet(s). A device not approved for branch circuit protection, such as a thermal cutout or motor
overload protective device, is not considered as the overcurrent device protecting the circuit.

(ii) Branch circuit - appliance means a branch circuit supplying energy to one or more outlets to
which appliances are to be connected, such circuits to have no permanently connected lighting
fixtures not a part of an appliance.

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24 CFR 3280.802(a)(7)(iii)

(iii) Branch circuit - general purpose means a circuit that supplies a number of outlets for lighting
and appliances.
(iv) Branch circuit - individual means a branch circuit that supplies only one utilization equipment.
(8) Cabinet means an enclosure designed either for surface or flush mounting, and provided with a
frame, mat, or trim in which swinging doors are hung.
(9) Circuit breaker means a device designed to open and close a circuit by nonautomatic means, and to
open the circuit automatically on a predetermined overload of current without injury to itself when
properly applied within its rating.
(10) Concealed means rendered inaccessible by the structure or finish of the manufactured home. Wires
in concealed raceways are considered concealed, even though they may become accessible by
withdrawing them. (See accessible (As applied to wiring methods))
(11) Connector, pressure (solderless) means a device that establishes a connection between two or more
conductors or between one or more conductors and a terminal by means of mechanical pressure
and without the use of solder.
(12) Dead front (as applied to switches, circuit-breakers, switchboards, and distribution panelboard)
means so designed, constructed, and installed that no current-carrying parts are normally exposed
on the front.
(13) Demand factor means the ratio of the maximum demand of a system, or part of a system, to the total
connected load of a system or the part of the system under consideration.
(14) Device means a unit of an electrical system that is intended to carry but not utilize electrical energy.
(15) Disconnecting means means a device, or group of devices, or other means by which the conductors
of a circuit can be disconnected from their source of supply.
(16) Distribution panelboard means a single panel or a group of panel units designed for assembly in the
form of a single panel, including buses, and with or without switches or automatic overcurrent
protective devices or both, for the control of light, heat, or power circuits of small individual as well
as aggregate capacity; designed to be placed in a cabinet placed in or against a wall or partition and
accessible only from the front.
(17) Enclosed means surrounded by a case that will prevent a person from accidentally contacting live
parts.
(18) Equipment means a general term, including material, fittings, devices, appliances, fixtures, apparatus,
and the like used as a part of, or in connection with, an electrical installation.
(19) Exposed
(i)

(As applied to live parts) means capable of being inadvertently touched or approached nearer
than a safe distance by a person. It is applied to parts not suitably guarded, isolated, or
insulated. (See accessible and concealed.)

(ii) (As applied to wiring method) means on or attached to the surface or behind panels designed to
allow access. (See Accessible (as applied to wiring methods))
(20) Externally operable means capable of being operated without exposing the operator to contact with
live parts.
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24 CFR 3280.802(a)(21)

(21) Feeder assembly means the overhead or under-chassis feeder conductors, including the grounding
conductor, together with the necessary fittings and equipment, or a power supply cord approved for
manufactured home use, designed for the purpose of delivering energy from the source of electrical
supply to the distribution panelboard within the manufactured home.
(22) Fitting means an accessory, such as a locknut, bushing, or other part of a wiring system, that is
intended primarily to perform a mechanical rather than an electrical function.
(23) Ground means a conducting connection, whether intentional or accidental, between an electrical
circuit or equipment and earth, or to some conducting body that serves in place of the earth.
(24) Grounded means connected to earth or to some conducting body that serves in place of the earth.
(25) Grounded conductor means a system or circuit conductor that is intentionally grounded.
(26) Grounding conductor means a conductor used to connect equipment or the grounded circuit of a
wiring system to a grounding electrode or electrodes.
(27) Guarded means covered, shielded, fenced, enclosed, or otherwise protected by means of suitable
covers, casings, barriers, rails, screens, mats or platforms to remove the likelihood of approach or
contact by persons or objects to a point of danger.
(28) Isolated means not readily accessible to persons unless special means for access are used.
(29) Laundry area means an area containing or designed to contain either a laundry tray, clothes washer
and/or clothes dryer.
(30) Lighting outlet means an outlet intended for the direct connection of a lampholder, a lighting fixture,
or a pendant cord terminating in a lampholder.
(31) Manufactured home accessory building or structure means any awning, cabana, ramada, storage
cabinet, carport, fence, windbreak or porch established for the use of the occupant of the
manufactured home upon a manufactured home lot.
(32) Manufactured home service equipment means the equipment containing the disconnecting means,
overcurrent protective devices, and receptacles or other means for connecting a manufactured
home feeder assembly.
(33) Outlet means a point on the wiring system at which current is taken to supply utilization equipment.
(34) Panelboard means a single panel or group of panel units designed for assembly in the form of a
single panel; including buses, automatic overcurrent protective devices, and with or without switches
for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box
placed in or against a wall or partition and accessible only from the front.
(35) Raceway means any channel for holding wires, cables, or busbars that is designed expressly for, and
used solely for, this purpose. Raceways may be of metal or insulating material, and the term includes
rigid metal conduit, rigid nonmetallic conduit, flexible metal conduit, electrical metallic tubing,
underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface
raceways, structural raceways, wireways, and busways.
(36) Raintight means so constructed or protected that exposure to a beating rain will not result in the
entrance of water.

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24 CFR 3280.802(a)(37)

(37) Readily accessible means capable of being reached quickly for operation, renewal, or inspection,
without requiring those to whom ready access is requisite to climb over or remove obstacles or to
resort to portable ladders, chairs, etc. (See Accessible.)
(38) Receptacle means a contact device installed at the outlet for the connection of an attachment plug.
A single receptacle is a single contact device with no other contact device on the same yoke. A
multiple receptacle is a device with two or more contact devices on the same yoke.
(39) Receptacle outlet means an outlet where one or more receptacles are installed.
(40) Utilization equipment means equipment that utilizes electric energy for electronic, electromechanical,
chemical, heating, lighting, or similar purposes.
(41) Voltage (of a circuit) means the greatest root-mean-square (effective) difference of potential
between any two conductors of the circuit concerned. Some systems, such as 3-phase 4-wire, singlephase 3-wire, and 3-wire direct-current may have various circuits of various voltages.
(42) Weatherproof means so constructed or protected that exposure to the weather will not interfere with
successful operation. Rainproof, raintight, or watertight equipment can fulfill the requirements for
weatherproof where varying weather conditions other than wetness, such as snow, ice, dust, or
temperature extremes, are not a factor.
(b) [Reserved]
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 78 FR 73989, Dec. 9, 2013; 86 FR 2523,
Jan. 12, 2021]

§ 3280.803 Power supply.
(a) The power supply to the manufactured home shall be a feeder assembly consisting of not more than one
listed 50 ampere manufactured home power-supply cords, or a permanently installed circuit. A
manufactured home that is factory-equipped with gas or oil-fired central heating equipment and cooking
appliances shall be permitted to be provided with a listed manufactured home power-supply cord rated 40
amperes.
(b) If the manufactured home has a power-supply cord, it shall be permanently attached to the distribution
panelboard or to a junction box permanently connected to the distribution panelboard, with the free end
terminating in an attachment plug cap.
(c) Cords with adapters and pigtail ends, extension cords, and similar items shall not be attached to, or
shipped with, a manufactured home.
(d) A suitable clamp or the equivalent must be provided at the distribution panelboard knockout to afford
strain relief for the cord to prevent strain from being transmitted to the terminals when the power supply
cord is handled in its intended manner.
(e) The cord shall be of an approved type with four conductors, one of which shall be identified by a
continuous green color or a continuous green color with one or more yellow stripes for use as the
grounding conductor.
(f) The attachment plug cap must be a 3-pole, 4-wire, grounding type, rated 50 amperes, 125/250 volts,
intended for use with the 50-ampere, 125/250-volt receptacle configuration, as shown below. The cap
must be listed, by itself or as part of a power-supply cord assembly, for the purpose, and must be molded
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24 CFR 3280.803(g)

to or installed on the flexible cord so that it is secured tightly to the cord at the point where the cord enters
the attachment plug cap. If a right-angle cap is used, the configuration must be so oriented that the
grounding member is farthest from the cord.

(g) The overall length of a power-supply cord, measured from the end of the cord, including bared leads, to the
face of the attachment-plug cap shall not be less than 21 feet and shall not exceed 361⁄2 feet. The length
of cord from the face of the attachment-plug cap to the point where the cord enters the manufactured
home shall not be less than 20 feet.
(h) The power supply cord shall bear the following marking: “For use with manufactured homes - 40 amperes”
or “For use with manufactured homes - 50 amperes.”
(i)

Where the cord passes through walls or floors, it must be protected by means of conduits and bushings or
the equivalent. The cord is permitted to be installed within the manufactured home walls, provided that a
continuous raceway having a maximum size of 11⁄4 inch is installed from the branch-circuit panelboard to
the underside of the manufactured home floor.

(j)

Permanent provisions shall be made for the protection of the attachment-plug cap of the power supply
cord and any connector cord assembly or receptacle against corrosion and mechanical damage if such
devices are in an exterior location while the manufactured home is in transit.

(k) Where the calculated load exceeds 50 amperes or where a permanent feeder is used, the supply shall be
by means of:
(1) One mast weatherhead installation installed in accordance with Article 230 of the National Electrical
Code, NFPA No. 70-2005, containing four continuous insulated, color-coded, feeder conductors, one
of which shall be an equipment grounding conductor; or
(2) A listed metal raceway or listed rigid nonmetallic conduit from the disconnecting means in the
manufactured home to the underside of the manufactured home, with provisions for the attachment
of a suitable junction box or fitting to the raceway on the underside of the manufactured home. The
manufacturer must provide written installation instructions stating the proper feeder conductor sizes
for the raceway and the size of the junction box to be used; or
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24 CFR 3280.803(k)(3)

(3) Service equipment installed in or on the manufactured home, provided that all of the following
conditions are met:
(i)

In its written installation instructions, the manufacturer must include information indicating that
the home must be secured in place by an anchoring system or installed on and secured to a
permanent foundation;

(ii) The installation of the service equipment complies with Article 230 of the National Electrical
Code, NFPA 70-2005 (incorporated by reference, see § 3280.4). Exterior service equipment or
the enclosure in which it is to be installed must be weatherproof, and conductors must be
suitable for use in wet locations;
(iii) Means are provided for the connection of the grounding electrode conductor to the service
equipment and routing it to the conductor outside the structure;
(iv) Bonding and grounding of the service must be in accordance with Article 250, NFPA 70-2005,
National Electrical Code (incorporated by reference, see § 3280.4);
(v) The manufacturer must include in its installation instructions one method of grounding the
service equipment at the installation site. The instructions must clearly state that other
methods of grounding are found in Article 250 of NFPA 70-2005, National Electrical Code;
(vi) The minimum size grounding electrode conductor must be specified in the instructions; and
(vi) A red warning label must be mounted on or adjacent to the service equipment. The label must
state the following: WARNING - DO NOT PROVIDE ELECTRICAL POWER UNTIL THE
GROUNDING ELECTRODE(S) IS INSTALLED AND CONNECTED (SEE INSTALLATION
INSTRUCTIONS).
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 4589, Feb. 12, 1987; 58 FR 55019,
Oct. 25, 1993; 70 FR 72051, Nov. 30, 2005; 78 FR 73990, Dec. 9, 2013]

§ 3280.804 Disconnecting means and branch-circuit protective equipment.
(a) The branch-circuit equipment is permitted to be combined with the disconnecting means as a single
assembly. Such a combination is permitted to be designated as a distribution panelboard. If a fused
distribution panelboard is used, the maximum fuse size for the mains shall be plainly marked, with the
lettering at least 1/4-inch high and visible when fuses are changed. See Article 110-22 of NFPA 70-2005,
National Electrical Code (incorporated by reference, see § 3280.4), concerning the identification of each
disconnecting means and each service, feeder, or branch circuit at the point where it originated, and the
type of marking needed.
(b) Plug fuses and fuseholders shall be tamper-resistant, Type “S,” enclosed in dead-front fuse panelboards.
Electrical distribution panels containing circuit breakers shall also be dead-front type.
(c) Disconnecting means. A single disconnecting means must be provided in each manufactured home,
consisting of a circuit breaker, or a switch and fuses and its accessories, installed in a readily accessible
location near the point of entrance of the supply cord or conductors into the manufactured home. The
main circuit breakers or fuses must be plainly marked “Main.” This equipment must contain a solderless
type of grounding connector or bar for the purposes of grounding, with sufficient terminals for all
grounding conductors. The neutral bar termination of the grounded circuit conductors must be insulated
in accordance with § 3280.809(b).
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24 CFR 3280.804(d)

(d) The disconnecting equipment shall have a rating suitable for the connected load. The distribution
equipment, either circuit breaker or fused type, shall be located a minimum of 24 inches from the bottom
of such equipment to the floor level of the manufactured home.
(e) A distribution panelboard employing a main circuit breaker must be rated not less than 50 amperes and
employ a 2-pole circuit breaker rated 40 amperes for a 40-ampere supply cord, or 50 amperes for a
50-ampere supply cord. A distribution panelboard employing a disconnect switch and fuses must be rated
not less than 60 amperes and must employ a single, 2-pole fuseholder rated not less than 60-amperes
with 40- or 50-ampere main fuses for 40- or 50-ampere supply cords, respectively. The outside of the
distribution panelboard must be plainly marked with the fuse size.
(f) The distribution panelboard must be located in an accessible location, and must not be located in a
bathroom or a clothes closet. A clear working space at least 30 inches wide and 30 inches in front of the
distribution panelboard must be provided. This space must extend from the floor to the top of the
distribution panelboard. Where used as switches, circuit breakers must be installed so that the center of
the grip of the operating handle of the circuit breaker, when in its highest position, will not be more than 6
feet, 7 inches above the floor.
(g) Branch-circuit distribution equipment shall be installed in each manufactured home and shall include
overcurrent protection for each branch circuit consisting of either circuit breakers or fuses.
(1) The branch circuit overcurrent devices shall be rated:
(i)

Not more than the circuit conductors; and

(ii) Not more than 150 percent of the rating of a single appliance rated 13.3 amperes or more which
is supplied by an individual branch circuit; but
(iii) Not more than the fuse size marked on the air conditioner or other motor-operated appliance.
(h) A 15-ampere multiple receptacle shall be acceptable when connected to a 20-ampere laundry circuit.
(i)

When circuit breakers are provided for branch-circuit protection 240 circuits shall be protected by 2-pole
common or companion trip, or handle-tied paired circuit breakers.

(j)

A 3 inch by 1-3/4 inch minimum size tag made of etched, metal-stamped or embossed brass, stainless
steel, anodized or alclad aluminum not less than 0.020 inch thick, or other approval material (e.g., 0.005
inch plastic laminates) shall be permanently affixed on the outside adjacent to the feeder assembly
entrance and shall read: This connection for 120/240 Volt, 3-Pole, 4-Wire, 60 Hertz, ________ Ampere
Supply. The correct ampere rating shall be marked on the blank space.

(k) When a home is provided with installed service equipment, a single disconnecting means for
disconnecting the branch circuit conductors from the service entrance conductors must be provided in
accordance with Article 230, Part VI of the National Electrical Code, NFPA No. 70-2005. The disconnecting
means shall be listed for use as service equipment. The disconnecting means may be combined with the
disconnect required by § 3280.804(c). The disconnecting means shall be rated not more than the ampere
supply or service capacity indicated on the tag required by paragraph (l) of this section.
(l)

When a home is provided with installed service equipment, the electrical nameplate required by §
3280.804(j) shall read: “This connection for 120/240 volt, 3 pole, 3 wire, 60 Hertz, ________ Ampere
Supply.” The correct ampere rating shall be marked in the blank space.

[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 961, Jan. 4, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at
52 FR 4589, Feb. 12, 1987; 58 FR 55019, Oct. 25, 1993; 70 FR 72051, Nov. 30, 2005; 78 FR 73990, Dec. 9, 2013]
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24 CFR 3280.805

§ 3280.805 Branch circuits required.
(a) The number of branch circuits required shall be determined in accordance with the following:
(1) Lighting, based on 3 volt-amperes per square foot times outside dimensions of the manufactured
home (coupler excluded) divided by 120 volts times amperes to determine number of 15 or 20
ampere lighting area circuits. e.g. [3 × length × width - [120 × (15 or 20)] = number of 15 or 20 ampere
circuits. Lighting circuits are permitted to serve built-in gas ovens with electric service for lights,
clocks, or timers, or for listed cord-connected garbage disposal units.
(2) Small Appliances. For the small appliance load in kitchens, pantries, dining rooms, and breakfast
rooms of manufactured homes, two or more 20-ampere appliance branch circuits, in addition to the
branch circuit specified in paragraph (a)(1) of this section, must be provided for all receptacle outlets
in these rooms, and such circuits must have no other outlets. Countertop receptacle outlets installed
in the kitchen must be supplied by not less than two small appliance branch circuits. One or more of
the small appliance branch circuits may also supply other receptacle outlets in the kitchen, pantry,
dining room, and breakfast room. Receptacles installed solely for the electrical supply to an electric
clock and receptacles installed to provide power for supplemental equipment and lighting on gasfired ranges, ovens, or counter-mounted cooking units are not subject to the requirements of this
paragraph (a)(2).
(3) General appliances (Including furnace, water heater, range, and central or room air conditioner, etc.).
There shall be one or more circuits of adequate rating in accordance with the following:
(i)

The ampere rating of fixed appliances must not exceed 50 percent of the circuit rating if lighting
outlets are on the same circuit (receptacles in the kitchen, dining area, and laundry are not
considered to be lighting outlets);

(ii) For fixed appliances on a circuit without lighting outlets, the sum of rated amperes shall not
exceed the branch-circuit rating. Motor loads or other continuous duty loads shall not exceed
80 percent of the branch circuit rating.
(iii) The rating of a single cord and plug connected appliances on a circuit having no other outlets,
shall not exceed 80 percent of the circuit rating.
(iv) The rating of the range branch circuit is based on the range demand as specified for ranges in §
3280.811(a)(5). For central air conditioning, see Article 440 of the National Electrical Code,
NFPA No. 70-2005.
(v) Where a laundry area is provided, a 20 ampere branch circuit shall be provided to supply laundry
receptacle outlets. This circuit shall have no other outlets. See § 3280.806(a)(7).
(vi) Bathroom receptacle outlets must be supplied by at least one 20-ampere branch circuit. Such
circuits must have no other outlets, except that it is permissible to place the receptacle outlet
for a heat tape or pipe heating cable required by § 3280.806(d)(10) on a bathroom circuit. (See
§ 3280.806(b).)
(b) [Reserved]
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55020, Oct. 25, 1993; 70 FR 72051,
Nov. 30, 2005; 78 FR 73991, Dec. 9, 2013]

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24 CFR 3280.806

§ 3280.806 Receptacle outlets.
(a) All receptacle outlets shall be:
(1) Of grounding type;
(2) Installed according to Article 406.3 of the National Electrical Code, NFPA No. 70-2005.
(3) Except when supplying specific appliances, be parallel-blade, 15-ampere, 125-volt, either single or
duplex.
(b) All 125-volt, single-phase, 15- and 20-ampere receptacle outlets installed outdoors, or in compartments
accessible from outside the manufactured home, and in bathrooms, including receptacles in light fixtures,
must have ground-fault circuit-interrupter protection for personnel. Ground-fault circuit-interrupter
protection for personnel must be provided for receptacles serving countertops in kitchens and receptacle
outlets located within 6 feet of a wet bar sink, except for receptacles installed for appliances in dedicated
spaces, such as dishwashers, disposals, refrigerators, freezers, and laundry equipment.
(c) There shall be an outlet of the grounding type for each cord-connected fixed appliance installed.
(d) Receptacle outlets required. Except in the bath, closet, and hall areas, receptacle outlets must be installed
at wall spaces 2 feet or more wide, so that no point along the floor line is more than 6 feet, measured
horizontally, from an outlet in that space. Receptacle outlets in floors shall not be counted as part of the
required number of receptacle outlets, unless located within 18 inches of the wall. In addition, a
receptacle outlet must be installed in the following locations:
(1) Over or adjacent to counter tops in the kitchen (at least one on each side of the sink if counter tops
are on each side and 12 inches or over in width).
(2) Adjacent to the refrigerator and free-standing gas-range space. A duplex receptacle may serve as the
outlet for a countertop and a refrigerator.
(3) At counter top spaces for built-in vanities.
(4) At counter top spaces under wall-mounted cabinets.
(5) In the wall, at the nearest point where a bar type counter attaches to the wall.
(6) In the wall at the nearest point where a fixed room divider attaches to the wall.
(7) In laundry areas within 6 feet of the intended location of the appliance(s).
(8) At least one receptacle outlet shall be installed outdoors.
(9) At least one wall receptacle outlet shall be installed in bathrooms within 36 inches (914 mm) of the
outside edge of each basin. The receptacle outlet must be located on a wall that is adjacent to the
basin location. This receptacle is in addition to any receptacle that is part of a lighting fixture or
appliance. The receptacle must not be enclosed within a bathroom cabinet or vanity.
(10) On the underside of the home for the connection of pipe heating cable(s) or heat tape(s), and the
outlet must:
(i)

Be located within 2 feet of the cold water inlet;

(ii) Be connected to an interior branch circuit, other than a small appliance branch circuit;

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24 CFR 3280.806(d)(10)(iii)

(iii) Be located on a circuit where all of the outlets are on the load side of the ground-fault circuitinterrupter protection for personnel; and
(iv) Not be considered as the receptacle outlet required by paragraph (8) of this section.
(11) Receptacle outlets are not required in the following locations:
(i)

Wall space occupied by built-in kitchen or wardrobe cabinets,

(ii) Wall space behind doors which may be opened fully against a wall surface,
(iii) Room dividers of the lattice type, less than 8 feet long, not solid within 6 inches of the floor,
(iv) Wall space afforded by bar type counters.
(e) Receptacle outlets shall not be installed in or within reach (30 inches) of a shower or bathtub space.
(f) Receptacle outlets shall not be installed above electric baseboard heaters.
(g) Receptacles must not be in a face-up position in any countertop.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55020, Oct. 25, 1993; 70 FR 72052,
Nov. 30, 2005; 78 FR 73991, Dec. 9, 2013]

§ 3280.807 Fixtures and appliances.
(a) Electrical materials, devices, appliances, fittings, and other equipment installed, intended for use in, or
attached to the manufactured home shall be approved for the application and shall be connected in an
approved manner when in service. Facilities shall be provided to securely fasten appliances when the
manufactured home is in transit. (See § 3280.809.)
(b) Specifically listed pendant-type fixtures or pendant cords shall be permitted in manufactured homes.
(c) Where a lighting fixture is installed over a bathtub or in a shower stall, it must be listed for wet locations.
[See also Article 410.4(D) of the National Electrical Code NFPA No. 70-2005.]
(d) The switch for shower lighting fixtures and exhaust fans located over a tub or in a shower stall shall be
located outside the tub shower space. (See § 3280.806(e).)
(e) Any combustible wall or ceiling finish exposed between the edge of a fixture canopy, or pan and an outlet
box shall be covered with non-combustible or limited combustible material.
(f) Every appliance shall be accessible for inspection, service, repair, or replacement without removal of
permanent construction.
(g) In bathrooms, ceiling-mounted lighting fixtures and wall-mounted lighting fixtures must not be controlled
by the same switch.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 52 FR 35543, Sept. 22, 1987; 58 FR
55020, Oct. 25, 1993; 70 FR 72052, Nov. 30, 2005; 78 FR 73991, Dec. 9, 2013; 86 FR 2523, Jan. 12, 2021]

§ 3280.808 Wiring methods and materials.
(a) Except as specifically permitted by this part, the wiring methods and materials specified in the National
Electrical Code, NFPA No. 70-2005, must be used in manufactured homes.
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24 CFR 3280.808(b)

(b) Nonmetallic outlet boxes shall be acceptable only with nonmetallic cable.
(c) Nonmetallic cable located 15 inches or less above the floor, if exposed, shall be protected from physical
damage by covering boards, guard strips, or conduit. Cable likely to be damaged by stowage shall be so
protected in all cases.
(d) Nonmetallic sheathed cable shall be secured by staples, straps, or similar fittings so designed and
installed as not to injure any cable. Cable shall be secured in place at intervals not exceeding 41⁄2 feet and
within 12 inches from every cabinet, box or fitting.
(e) Metal-clad and nonmetallic cables shall be permitted to pass through the centers of the wide side of
2-inch by 4-inch studs. However, they shall be protected where they pass through 2-inch by 2-inch studs or
at other studs or frames where the cable or armor would be less than 11⁄2 inches from the inside or
outside surface of the studs when the wall covering materials are in contact with the studs. Steel plates
on each side of the cable, or a tube, with not less than No. 16 MSG wall thickness shall be required to
protect the cable. These plates or tubes shall be securely held in place.
(f) Where metal faceplates are used, they must be effectively grounded.
(g) If the range, clothes dryer, or similar appliance is connected by metalclad cable or flexible conduit, a length
of not less than three feet of free cable or conduit shall be provided to permit moving the appliance. Type
NM or Type SE cable shall not be used to connect a range or a dryer. This shall not prohibit the use of
Type NM or Type SE cable between the branch circuit overcurrent protective device and a junction box or
range or dryer receptacle.
(h) Where rigid metal conduit or intermediate metal conduit is terminated at an enclosure with a locknut and
bushing connection, two locknuts must be provided, one inside and one outside of the enclosure. Rigid
nonmetallic conduit or electrical nonmetallic tubing is permitted. All cut ends of conduit and tubing must
be reamed or otherwise finished to remove rough edges.
(i)

Switches must be rated as follows:
(1) For lighting circuits, switches must be rated not less than 10 amperes, 120 to 125 volts, and in no
case less than the connected load.
(2) For motors or other loads, switches shall have ampere or horsepower ratings, or both, adequate for
loads controlled. (An “AC general-use” snap switch shall be permitted to control a motor 2
horsepower or less with full-load current not over 80 percent of the switch ampere rating).

(j)

At least 4 inches of free conductor shall be left at each outlet box except where conductors are intended
to loop without joints.

(k) When outdoor or under-chassis line-voltage (120 volts, nominal or higher) wiring is exposed to moisture or
physical damage, it must be protected by rigid metal conduit or intermediate metal conduit. The
conductors must be suitable for wet locations. Electrical metallic tubing or rigid nonmetallic conduit is
permitted to be used when closely routed against frames and equipment enclosures.
(l)

Outlet boxes of dimensions less than those required in Table 314.16(A) of the National Electrical Code,
NFPA No. 70-2005, are permitted provided the box has been tested and approved for that purpose.

(m) Boxes, fittings, and cabinets shall be securely fastened in place, and shall be supported from a structural
member of the home, either directly or by using a substantial brace. Snap-in type boxes provided with
special wall or ceiling brackets that securely fasten boxes in walls or ceilings shall be permitted.
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24 CFR 3280.808(n)

(n) Outlet boxes must fit closely to openings in combustible walls and ceilings and must be flush with the
finish surface or project therefrom. In walls and ceilings of noncombustible material, outlet boxes and
fittings must be installed so that the front edge of the box or fitting will not be set back from the finished
surface more than 1⁄4 inch. Plaster, drywall, or plasterboard surfaces that are broken or incomplete must
be repaired so that there will be no gaps or open spaces greater than 1⁄8 inch at the edge of the box or
fitting.
(o) Appliances having branch-circuit terminal connections which operate at temperatures higher than 60 °C
(140 °F) shall have circuit conductors as described in paragraphs (p) (1) and (2) of this section:
(1) Branch-circuit conductors having an insulation suitable for the temperature encountered shall be
permitted to run directly to the appliance.
(2) Conductors having an insulation suitable for the temperature encountered may be run from the
appliance terminal connections to a readily accessible outlet box placed at least one foot from the
appliance. If provided, these conductors must be in a suitable raceway or Type AC or MC cable, of at
least 18 inches but not more than 6 feet in length.
(p) A substantial brace for securing a box, fitting, or cabinet must be as described in the National Electrical
Code, NFPA 70-2005, Article 314.23(B), or the brace, including the fastening mechanism to attach the
brace to the home structure, must withstand a force of 50 lbs. applied to the brace at the intended
point(s) of attachment for the box in a direction perpendicular to the surface on which the box is installed.
(q) Where the sheathing of NM cable has been cut or damaged and visual inspection reveals that the
conductor and its insulation has not been damaged, it shall be permitted to repair the cable sheath with
electrical tape which provides equivalent protection to the sheath.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55020, Oct. 25, 1993; 70 FR 72052,
Nov. 30, 2005; 78 FR 73991, Dec. 9, 2013]

§ 3280.809 Grounding.
(a) General. Grounding of both electrical and nonelectrical metal parts in a manufactured home shall be
through connection to a grounding bus in the manufactured home distribution panelboard. The grounding
bus shall be grounded through the green-colored conductor in the supply cord or the feeder wiring to the
service ground in the service-entrance equipment located adjacent to the manufactured home location.
Neither the frame of the manufactured home nor the frame of any appliance shall be connected to the
neutral conductor in the manufactured home.
(b) Insulated neutral.
(1) The grounded circuit conductor (neutral) shall be insulated from the grounding conductors and from
equipment enclosures and other grounded parts. The grounded (neutral) circuit terminals in the
distribution panelboard and in ranges, clothes dryers, counter-mounted cooking units, and wallmounted ovens shall be insulated from the equipment enclosure. Bonding screws, straps, or buses
in the distribution panelboard or in appliances shall be removed and discarded. However, when
service equipment is installed on the manufactured home, the neutral and the ground bus may be
connected in the distribution panel.

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24 CFR 3280.809(b)(2)

(2) Connection of ranges and clothes dryers with 120/240 volt, 3-wire ratings shall be made with 4
conductor cord and 3 pole, 4-wire grounding type plugs, or by type AC metal clad conductors
enclosed in flexible metal conduit. For 120 volt rated devices a 3-conductor cord and a 2-pole, 3-wire
grounding type plug shall be permitted.
(c) Equipment grounding means.
(1) The green-colored grounding wire in the supply cord or permanent feeder wiring shall be connected
to the grounding bus in the distribution panelboard or disconnecting means.
(2) In the electrical system, all exposed metal parts, enclosures, frames, lamp fixture canopies, etc., shall
be effectively bonded to the grounding terminal or enclosure of the distribution panelboard.
(3) Cord-connected appliances, such as washing machines, clothes dryers, refrigerators, and the
electrical system of gas ranges, etc., shall be grounded by means of an approved cord with
grounding conductor and grounding-type attachment plug.
(d) Bonding of noncurrent-carrying metal parts.
(1) All exposed noncurrent-carrying metal parts that may become energized shall be effectively bonded
to the grounding terminal or enclosure of the distribution panelboard. A bonding conductor shall be
connected between each distribution panelboard and an accessible terminal on the chassis.
(2) Grounding terminals shall be of the solderless type and approved as pressure-terminal connectors
recognized for the wire size used. Star washers or other approved paint-penetrating fitting shall be
used to bond terminals to chassis or other coated areas. The bonding conductor shall be solid or
stranded, insulated or bare and shall be No. 8 copper minimum, or equal. The bonding conductor
shall be routed so as not to be exposed to physical damage. Protection can be afforded by the
configuration of the chassis.
(3) Metallic gas, water and waste pipes and metallic air-circulating ducts shall be considered bonded if
they are connected to the terminal on the chassis (see § 3280.809) by clamps, solderless
connectors, or by suitable grounding-type straps.
(4) Any metallic roof and exterior covering shall be considered bonded if
(i)

the metal panels overlap one another and are securely attached to the wood or metal frame
parts by metallic fasteners, and

(ii) if the lower panel of the metallic exterior covering is secured by metallic fasteners at a cross
member of the chassis by two metal straps per manufactured home unit or section at opposite
ends. The bonding strap material shall be a minimum of 4 inches in width of material equivalent
to the skin or a material of equal or better electrical conductivity. The straps shall be fastened
with paint-penetrating fittings (such as screws and star washers or equivalent).
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55020, Oct. 25, 1993]

§ 3280.810 Electrical testing.
(a) Dielectric strength test. The wiring of each manufactured home shall be subjected to a 1-minute, 900 to
1079 volt dielectric strength test (with all switches closed) between live parts and the manufactured
home ground, and neutral and the manufactured home ground. Alternatively, the test may be performed at

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24 CFR 3280.810(b)

1080 to 1250 volts for 1 second. This test shall be performed after branch circuits are complete and after
fixtures or appliances are installed. Fixtures or appliances which are listed shall not be required to
withstand the dielectric strength test.
(b) Additional testing. Each manufactured home must be subjected to the following tests:
(1) An electrical continuity test to assure that metallic parts are effectively bonded;
(2) An operational test of all devices and utilization equipment, except water heaters, electric ranges,
electric furnaces, dishwashers, clothes washers/dryers, and portable appliances, to demonstrate
they are connected and in working order; and
(3) Electrical polarity checks to determine that connections have been made in accordance with
applicable provisions of these standards and Article 550.17 of NFPA 70-2005 (incorporated by
reference, see § 3280.4). Visual verification is an acceptable electrical polarity check.
[58 FR 55020, Oct. 25, 1993, as amended at 86 FR 2523, Jan. 12, 2021]

§ 3280.811 Calculations.
(a) The following method shall be employed in computing the supply cord and distribution-panelboard load
for each feeder assembly for each manufactured home and shall be based on a 3-wire, 120/240 volt
supply with 120 volt loads balanced between the two legs of the 3-wire system. The total load for
determining power supply by this method is the summation of:
(1) Lighting and small appliance load as calculated below:
(i)

Lighting volt-amperes: Length time width of manufactured home (outside dimensions exclusive
of coupler) times 3 volt-amperes per square foot; e.g. Length × width × 3 = lighting voltamperes.

(ii) Small appliance volt-amperes: Number of circuits time 1,500 volt-amperes for each 20-ampere
appliance receptacle circuit (see definition of “Appliance Portable” with Note): e.g. Number of
circuits × 1,500 = small appliance volt-amperes.
(iii) Total volts-amperes: Lighting volts-amperes plus small appliance = total volt-amperes.
(iv) First 3,000 total volts-amperes at 100 percent plus remainder at 35 percent = watts to be
divided by 240 volts to obtain current (amperes) per leg.
(2) Nameplate amperes for motors and heater loads (exhaust fans, air conditioners, electric, gas, or oil
heating). Omit smaller of air conditioning and heating except include blower motor if used as air
conditioner evaporator motor. When an air conditioner is not installed and a 40-ampere power supply
cord is provided, allow 15 amperes per leg for air conditioning.
(3) 25 percent of current of largest motor in paragraph (a)(2) of this section.
(4) Total of nameplate amperes for: Disposal, dishwasher, water heater, clothes dryer, wall-mounted
oven, cooking units. Where number of these appliances exceeds three, use 75 percent of total.

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24 CFR 3280.811(a)(5)

(5) Derive amperes for free-standing range (as distinguished from separate ovens and cooking units) by
dividing values below by 240 volts.
Nameplate rating (in watts)

Use (in watts)

10,000 or less

80 percent of rating.

10,001 to 12,500

8,000.

12,501 to 13,500

8,400.

13,501 to 14,500

8,800.

14,501 to 15,500

9,200.

15,501 to 16,500

9,600.

16,501 to 17,500

10,000.

(6) If outlets or circuits are provided for other than factory-installed appliances, include the anticipated
load. The following example is given to illustrate the application of this Method of Calculation:

Example: A manufactured home is 70 × 10 feet and has two portable appliance circuits, a
1000 volt-ampere 240 volt heater, a 200 volt-ampere 120 volt exhaust fan, a 400 volts-ampere
120 volt dishwasher and a 7000 volt-ampere electric range.
Lighting and small appliance load

Volt-ampheres

Lighting 70 × 10 × 3

2,100

Small Appliance

3,000

Total

5,100

1st. 3,000 Volt-Ampheres at 100%

3,000

Remainder (5,100 −3,000 = 2,100, at 35%

735

Total

3,735
Amperes per leg A

Lighting and small Appliance

Amperes per leg B
15.5

15.5

Heater 240 volt

4.1

4.1

Fan 120 volt

1.7

Dishwasher 120 volt
Range
Total

3.3
23.3

23.3

44.6

46.2

Note: Based on the higher current calculated for either leg, use one 50-A supply cord.
(b) The following is an optional method of calculation for lighting and appliance loads for manufactured
homes served by single 3-wire 120/240 volt set of feeder conductors with an ampacity of 100 or greater.
The total load for determining the feeder ampacity may be computed in accordance with the following
table instead of the method previously specified. Feeder conductors whose demand load is determined by

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24 CFR 3280.811(b)(1)

this optional calculation are permitted to have the neutral load determined by Article 220.61 of the
National Electrical Code, NFPA No. 70-2005. The loads identified in the table as “other load” and as
“Remainder of other load” must include the following:
(1) 1500 volt-amperes for each 2-wire, 20-ampere small appliance branch circuit and each laundry
branch circuit specified.
(2) 3 volt-amperes per square foot for general lighting and general-use receptacles.
(3) The nameplate rating of all fixed appliances, ranges, wall-mounted ovens, counter-mounted cooking
units, and including 4 or more separately controlled space heating loads.
(4) The nameplate ampere or kVA rating of all motors and of all low-power-factor loads.
(5) The largest of the following:
(i)

Air conditioning load;

(ii) The 65 percent diversified demand of the central electric space heating load;
(iii) The 65 percent diversified demand of the load of less than four separately-controlled electric
space heating units.
(iv) The connected load of four or more separately-controlled electric space heating units.

Optional Calculation for Manufactured Homes With 110-Ampere or Larger
Service
Load (in kilowatt or kilovoltampere)
Air-conditioning and cooling including heat pump compressors

Demand factor
(percent)
100

Central electric space heating

65

Less than 4 separately controlled electric space heating units

65

1st 10 kW of all other load
Remainder of other load

100
40

[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55021, Oct. 25, 1993; 70 FR 72052,
Nov. 30, 2005]

§ 3280.812 Wiring of expandable units and dual units.
(a) Expandable or multiple unit manufactured homes shall use fixed-type wiring methods and materials for
connecting such units to each other.
(b) Expandable or multiple unit manufactured homes not having permanently installed feeders and which are
to be moved from one location to another, shall be permitted to have disconnecting means with branch
circuit protective equipment in each unit when so located that after assembly or joining together of units
the requirements of § 3280.803 will be met.

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24 CFR 3280.813

§ 3280.813 Outdoor outlets, fixtures, air-conditioning equipment, etc.
(a) Outdoor fixtures and equipment shall be listed for use in wet locations, except that if located on the
underside of the home or located under roof extensions or similarly protected locations, they may be
listed for use in damp locations.
(b) A manufactured home provided with a branch circuit designed to energize outside heating equipment or
air-conditioning equipment, other than room air conditioners, or both, located outside the manufactured
home, other than room air conditioners, must have such branch-circuit conductors terminate in a listed
outlet box, or disconnecting means, located on the outside of the manufactured home.
(1) A label must be permanently affixed adjacent to the outlet box. The label must be not less than
0.020-inches thick etched brass, stainless steel, anodized or alclad aluminum, or equivalent, and
must not be less than 3 inches × 13⁄4 inches in size.
(2)
(i)

The label must include the correct voltage and ampere rating and the following information:

THIS CONNECTION IS FOR HEATING AND/OR AIR-CONDITIONING EQUIPMENT. THE BRANCH
CIRCUIT IS RATED AT NOT MORE THAN____AMPERES, AT____VOLTS, 60-HERTZ,____CONDUCTOR
AMPACITY. A DISCONNECTING MEANS IS LOCATED WITHIN SIGHT OF THE EQUIPMENT.
(ii) The correct voltage and ampere rating shall be given. The tag must be not less than
0.020-inches thick etched brass, stainless steel, anodized or alclad aluminum, or equivalent.
The tag must have a minimum size of not less than 3 inches × 13⁄4 inches.
[40 FR 58752, Dec. 18, 1975, as amended at 42 FR 961, Jan. 4, 1977. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at
58 FR 55021, Oct. 25, 1993; 78 FR 73992, Dec. 9, 2013]

§ 3280.814 Painting of wiring.
During painting or staining of the manufactured home, it shall be permitted to paint metal raceways (except where
grounding continuity would be reduced) or the sheath of the nonmetallic cable. Some arrangement, however, shall
be made so that no paint shall be applied to the individual wires, as the color coding may be obliterated by the paint.

§ 3280.815 Polarization.
(a)
(1) Except as provided in paragraph (a)(2) of this section, the white conductor must be employed for the
grounded (neutral) circuit conductors only and must be connected to the white terminal or lead on
receptacle outlets and fixtures. The grounded conductor must be the unswitched wire in switched
circuits.
(2) A cable containing an insulated conductor with a white or natural gray outer finish or a marking of
three continuous white stripes may be used for single-pole, three-way, or four-way switch loops,
where this conductor is used for the supply to the switch, but not as a return conductor from the
switch to the switched outlet. In these applications, the conductor with white or natural gray
insulation or with three continuous white stripes must be permanently re-identified to indicate its use
by painting or other effective means at its terminations and at each location where the conductor is
visible and accessible.
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24 CFR 3280.815(b)

(b) If the identified (white) conductor of a cable is used for other than grounded conductors or for other than
switch loops as explained above (for a 240 volt circuit for example), the conductor shall be finished in a
color other than white at each outlet where the conductors are visible and accessible.
(c) Green-colored wires or green with yellow stripe shall be used for grounding conductors only.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 58 FR 55021, Oct. 25, 1993; 78 FR 73992,
Dec. 9, 2013]

§ 3280.816 Examination of equipment for safety.
The examination or inspection of equipment for safety, according to this standard, shall be conducted under
uniform conditions and by organizations properly equipped and qualified for experimental testing, inspections of the
run of goods at factories, and service-value determinations through field examinations.

Subpart J - Transportation
§ 3280.901 Scope.
Subpart J of this standard covers the general requirement for designing the structure of the manufactured home to
fully withstand the adverse effects of transportation shock and vibration without degradation of the integrated
structure or of its component parts and the specific requirements pertaining to the transportation system and its
relationship to the structure.

§ 3280.902 Definitions.
(a) Chassis means the entire transportation system comprising the following subsystems: drawbar and
coupling mechanism, frame, running gear assembly, and lights.
(b) Drawbar and coupling mechanism means the rigid assembly, (usually a rigid substructure) upon which is
mounted a coupling mechanism, which connects the manufactured home's frame to the towing vehicle.
(c) Frame means the fabricated rigid substructure which provides considerable support to the affixed
manufactured home structure both during transport and on-site; and also provides a platform for
securement of the running gear assembly, the drawbar and coupling mechanism.
(d) Running gear assembly means the subsystem consisting of suspension springs, axles, bearings, wheels,
hubs, tires, and brakes, with their related hardware.
(e) Lights means those safety lights and associated wiring required by applicable U.S. Department of
Transportation regulations.
(f) Transportation system, (Same as chassis, above).
(g) Highway, includes all roads and streets to be legally used in transporting the manufactured home.
[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, as amended at 47 FR 28093, June 29, 1982; 86 FR 2523,
Jan. 12, 2021]

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24 CFR 3280.903

§ 3280.903 General requirements for designing the structure to withstand transportation
shock and vibration.
(a) General. The manufactured home and its transportation system (as defined in § 3280.902(f)) must
withstand the effects of highway movement such that the home is capable of being transported safely
and installed as a habitable structure. Structural, plumbing, mechanical, and electrical systems must be
designed to function after set-up. The home must remain weather protected during the transportation
sequence to prevent internal damage.
(b) Testing or analysis requirements. Suitability of the transportation system and home structure to withstand
the effects of transportation must be permitted to be determined by testing, or engineering analysis, or a
combination of the two as required by paragraphs (b)(1) and (2) of this section.
(1) Road tests. Tests must be witnessed by an independent registered professional engineer or
architect, manufacturer's IPIA or DAPIA, or by a recognized testing organization. Such testing
procedures must be part of the manufacturer's approved design.
(2) Engineering analysis. Engineering analysis methods based on the principles of mechanics and/or
structural engineering may be used to substantiate the adequacy of the transportation system to
withstand in-transit loading conditions. As transportation loadings are typically critical in the
longitudinal direction, analysis should, in particular, provide emphasis on design of longitudinal
structural components of the manufactured home (e.g., main chassis girder beams, sidewalls, and
rim joists, etc.). Notwithstanding, all structural elements necessary to the structural integrity of the
manufactured home during in-transit loading are also to be evaluated (e.g., transverse chassis
members and floor framing members, etc.).
(i)
(A) The summation of the design loads in paragraphs (b)(2)(i)(A)(1) through (3) of this section
may be used to determine the adequacy of the chassis in conjunction with the
manufactured home structure to resist in-transit loading:
(1) Dead load, the vertical load due to the weight of all structural and non-structural
components of the manufactured home at the time of shipment.
(2) Floor load, a minimum of 3 pounds per square foot.
(3) Dynamic loading factor, (0.25)[(b2iA) + (b2iB)].
(B) However, the in-transit design loading need not exceed twice the dead load of the
manufactured home.
(ii) To determine the adequacy of individual longitudinal structural components to resist the intransit design loading, a load distribution based on the relative flexural rigidity and shear
stiffness of each component may be utilized. For the purpose of loading distribution, the
sidewall may be considered to be acting as a “deep beam” in conjunction with other load
carrying elements in determining the relative stiffness of the integrated structure. Further, by
proper pre-cambering of the chassis assembly, additional loading may be distributed to the
chassis, and the remaining loading may be distributed to each of the load carrying members by
the relative stiffness principle.
(iii) The analysis is also to include consideration for:
(A) Location of openings in the sidewall during transport and, when appropriate,
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24 CFR 3280.903(b)(2)(iii)(B)

provisions for reinforcement of the structure and/or chassis at the opening.
(B) Sidewall component member sizing and joint-splice analysis (i.e., top and bottom plates,
etc.), and connections between load carrying elements.
[86 FR 2523, Jan. 12, 2021]

§ 3280.904 Specific requirements for designing the transportation system.
(a) General. The transportation system must be designed and constructed as an integrated unit which is safe
and suitable for its specified use. In operation, the transportation system must effectively respond to the
control of the towing vehicle tracking and braking, while traveling at applicable highway speeds and in
normal highway traffic conditions.
(b) Specific requirements (1) Drawbar. The drawbar must be constructed of sufficient strength, rigidity, and durability to safely
withstand those dynamic forces experienced during highway transportation. It must be securely
fastened to the manufactured home substructure.
(2) Coupling mechanism. The coupling mechanism (which is usually of the socket type) must be
securely fastened to the drawbar in such a manner as to assure safe and effective transfer of the
maximum loads, including dynamic loads, between the manufactured home structure and the hitchassembly of the towing vehicle. The coupling must be equipped with a manually operated
mechanism so adapted as to prevent disengagement of the unit while in operation. The coupling
must be so designed that it can be disconnected regardless of the angle of the manufactured home
to the towing vehicle.
(3) Chassis. The chassis, in conjunction with the manufactured home structure, must be constructed to
effectively sustain the design loads. The integrated structure must be capable of ensuring the
integrity of the complete manufactured home and ensuring against excessive deformation of
structural or finish members.
(4) Running gear assembly (i)

Design criteria. The design load used to size running gear components must be the gross static
dead weight minus the static tongue weight supported by the drawbar. Running gear must be
designed to accept shock and vibration, both from the highway and the towing vehicle and
effectively dampen these forces so as to protect the manufactured home structure from
damage and fatigue. Its components must be designed to facilitate routine maintenance,
inspection, and replacement.

(ii) Location. Location of the running gear assembly must be determined by documented
engineering analysis, taking into account the gross weight (including all contents), total length
of the manufactured home, the necessary coupling hitch weight, span distance, and turning
radius. Weights shall be checked with the home in a level position ready for transport. The
coupling weight must be not less than 12 percent nor more than 25 percent of the gross
weight.
(5) Spring assemblies. Spring assemblies (springs, hangers, shackles, bushings, and mounting bolts)
must be capable of supporting the running gear design loads, without exceeding maximum
allowable stresses for design spring assembly life as recommended by the spring assembly
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24 CFR 3280.904(b)(6)

manufacturer. The capacity of the spring system must ensure that under maximum operating load
conditions, sufficient clearance is maintained between the tire and manufactured home's frame or
structure to permit unimpeded wheel movement and for changing tires.
(6) Axles. Axles, and their connecting hardware, must be capable of supporting the static running gear
design loads, without exceeding maximum allowable design axle loads as recommended by the axle
manufacturer. The number and load capacity necessary to provide a safe tow must not be less than
those required to support the design load.
(i)

Recycled axles. Before reuse, all axles, including all component parts, must be reconditioned as
required pursuant to a program accepted by a nationally recognized testing agency. The
recycling program must be approved, and the axles must be labeled by a nationally recognized
testing agency. Recycled axles and their components must utilize compatible components and
be of the same size and rating as the original equipment.

(ii) [Reserved].
(7) Hubs and bearings. Hubs and bearings shall meet the requirements of § 3280.904(b)(3) and good
engineering practice. Both of these components shall be accessible for inspection, routine
maintenance and replacement of parts.
(8) Tires, wheels, and rims. Tires, wheels, and rims must be selected, sized, and fitted to axles so that
static dead load supported by the running gear does not exceed the load capacity of the tires. Tires
must not be loaded beyond the load rating marked on the sidewall of the tire or, in the absence of
such a marking, the load rating specified in any of the publications of any of the organizations listed
in Federal Motor Vehicle Safety Standard (FMVSS) No. 119 in 49 CFR 571.119, S5.1(b). Wheels and
rims must be sized in accordance with the tire manufacturer's recommendations as suitable for use
with the tires selected.
(i)

Inflation pressure. The load and cold inflation pressure imposed on the rim or wheel must not
exceed the rim and wheel manufacturer's instructions even if the tire has been approved for a
higher load or inflation. Tire cold inflation pressure limitations and the inflation pressure
measurement correction for heat must be as specified in 49 CFR 393.75(h).

(ii) Used tires. Whenever the tread depth is at least 1⁄16 inch as determined by a tread wear
indicator, used tires are permitted to be sized in accordance with 49 CFR 571.119. The
determination as to whether a used tire is acceptable must also include a visual inspection for
thermal and structural defects (e.g., dry rotting, excessive tire sidewall splitting, etc.). Used tires
with such structural defects must not be installed on manufactured homes.
(9) Brake assemblies (i)

Braking axles. The number, type, size, and design of brake assemblies required to assist the
towing vehicle in providing effective control and stopping of the manufactured home must be
determined and documented by engineering analysis. Those alternatives listed in §
3280.903(c) may be accepted in place of such an analysis. Unless substantiated in the design
to the satisfaction of the approval agency by either engineering analysis in accordance with §
3280.903(a)(1) or tests in accordance with paragraph (b)(9)(ii) of this section, there must be a
minimum of two axles equipped with brake assemblies on each manufactured home
transportable section.

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24 CFR 3280.904(b)(9)(ii)

(ii) Stopping distance. Brakes on the towing vehicle and the manufactured home (a drive-away/towaway) must be capable of ensuring that the maximum stopping distance from an initial speed
of 20 miles per hour does not exceed 35 feet in accordance with 49 CFR 393.52(d) for 2 or
fewer vehicles in drive away or tow away operation.
(iii) Electrical brake wiring. Brake wiring must be provided for each brake. The brake wire must not
be less than the value specified in the brake manufacturer's instructions. Aluminum wire, when
used, must be provided with suitable termination that is protected against corrosion.
(10) Lamps and associated wiring. Stop lamps, turn signal/lamps, and associated wiring must meet the
appropriate sections of FMVSS No. 108 in 49 CFR 571.108, which specify the performance and
location of these lamps and their wiring. The manufacturer may meet these requirements by utilizing
a temporary light/wiring harness, which has components that meet the FMVSS No. 108. The
temporary harness is permitted to be provided by the manufactured home transportation carrier.
[40 FR 58752, Dec. 18, 1975, as amended at 86 FR 2524, Jan. 12, 2021]

Subpart K - Attached Manufactured Homes and Special Construction Considerations
Source: 86 FR 2525, Jan. 12, 2021, unless otherwise noted.

§ 3280.1001 Scope.
This subpart covers the requirements for attached manufactured homes and other related construction associated
with manufactured homes not addressed elsewhere within this part.

§ 3280.1002 Definitions.
The following definitions are applicable to this subpart only:
Attached manufactured home. Two or more adjacent manufactured homes that are structurally independent
from foundation to roof and with open space on at least two sides, but which have the appearance of a
physical connection (i.e., zero lot line).
Fire separation wall. An adjoining wall of a manufactured home that separates attached manufactured homes
with a fire separation distance of less than three feet.

§ 3280.1003 Attached manufactured home unit separation.
(a) Separation requirements.
(1) Attached manufactured homes shall be separated from each other by a fire separation wall of not
less than 1-hour fire-resistive rating with exposure from both sides on each attached manufactured
home unit when rated based on tests in accordance with ASTM E119-05 (incorporated by reference,
see § 3280.4).
(2) Fire-resistance-rated floor/ceiling and wall assemblies shall extend to and be tight against the
exterior wall, and wall assemblies shall extend from the foundation to the underside of the roof
sheathing.
(b) Fire separation penetrations.
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24 CFR 3280.1003(b)(1)

(1) Fire rated fire separation walls must not contain through penetrations or openings.
(2) Membrane penetrations for electrical boxes are permitted on the living side of the wall under the
following conditions:
(i)

Steel electrical boxes not exceeding 16 square inches may be installed provided that the total
area of such boxes does not exceed 100 square inches in any 100 square feet wall area. Steel
electrical boxes in adjacent fire separation walls must be separated by a horizontal distance of
not less than 24 inches.

(ii) Listed 2-hour fire-resistant nonmetallic electrical boxes are installed in accordance with the
listings.
(iii) No other membrane penetrations are allowed.
(c) Continuity of walls. The fire separation walls for single-family attached dwelling units must be continuous
from the foundation to the underside of the roof sheathing, deck, or slab and must extend the full length
of the fire separation walls.
(d) Parapets.
(1) Parapets constructed in accordance with paragraph (d)(2) of this section must be provided for
attached manufactured homes as an extension of fire separation walls in accordance with the
following:
(i)

Where roof surfaces adjacent to the fire separation walls are at the same elevation, the parapet
must extend not less than 30 inches above the roof surfaces.

(ii) Where roof surfaces adjacent to the wall or walls are at different elevations and the higher roof
is not more than 30 inches above the lower roof surface, the parapet must not extend less than
30 inches above the lower roof surface.
(A) Parapets must be provided unless roofs are of a Class C roof covering and the roof
decking or sheathing is of noncombustible materials or approved fire-retardant-treated
wood for a distance of four feet on each side of the common fire separation walls; or one
layer of 5⁄8 inch Type X gypsum board or equivalent is installed directly beneath the roof
decking or sheathing for a distance of four feet on each side of the fire separation walls.
(B) A parapet must not be required where roof surfaces adjacent to the common walls are at
different elevations and the higher roof is more than 30 inches above the lower roof. The
fire separation wall construction from the lower roof to the underside of the higher roof
deck must not have less than a 1-hour fire-resistive rating. The wall must be rated for
exposure from both sides.
(2) Parapets must have the same fire resistance rating as that required for the supporting wall or walls.
On any side adjacent to a roof surface, the parapet must have noncombustible faces for the
uppermost 18 inches, to include counter flashing and coping materials. Where the roof slopes
toward a parapet at slopes greater than 2⁄12 (16.7 percent slope), the parapet must extend to the
same height as any portion of the roof within a distance of three feet, but in no case will the height
be less than 30 inches.

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24 CFR 3280.1004

§ 3280.1004 Exterior walls.
(a) The requirements of § 3280.504 for condensation control and vapor retarder installation are required to
be provided on each fire separation wall of each attached manufactured home.
(b) The requirements of § 3280.506 for heat loss/gain insulation apply to the fire separation wall on each
attached manufactured home.

§ 3280.1005 Electrical service.
(a) Each attached manufactured home must be supplied by only one service.
(b) Service conductors supplying one manufactured home must not pass through the interior of another
manufactured home.

§ 3280.1006 Water service.
(a) Each manufactured home must have an individual water supply that will service only that unit.
(b) Each manufactured home must have a hot water supply system that will service only that unit.

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